pysis judo
TRANSCRIPT
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 18
r
The Physics Of Forces In Judo
Making The Weak Equal To TheStrong
By Jearl Walker
Judo is a martial art that demands an intuitive understanding of the physics of forces torques stability and rotational motionThis article examines a few of the basic throws of this form of combat The grace that each throw requires is not easily
conveyed but each throw can be broken into components thatcan be examined in terms of classical physics The experiments Ishall describe call for actual performance of the throws but youshould do them only under expert supervision since Judo if performed incorrectly can be dangerous to you and youropponent
In judo the main goal is to overcome your opponentrsquos stabilityThe skill lies in the anticipation of his movements and the timing
of your response The idea is to avoid forcing your opponent intoa firm resistance to your throw that would pit your strength
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 28
t
against his A small but skilled budo player has a distinctadvantage over a larger but unskilled opponent if the contest of strength is avoided
The Basic Hip Throw
The basic hip throw in Judo
Probably the best example of thisadvantage is the basic hip throwwhich is most effective against ataller and slower opponent In thenormal judo competition you faceyour opponent with your hands
grasping the lapels or shoulders of his uniform To execute the throwyou step forward with your rightfoot to a point in between his feetpulling him downward and toward
your right The throw works well if you have caught your opponent
just as he has stepped forward with
his right foot He is still stableagainst a pull directly toward you
but is considerably less stableagainst a pull to your right becauseof the position of his feet
The footwork in the hip throw
During your step forward you curve your body forward so that
your head is at your opponentrsquos shoulder level Next you rapidlyturn your left hip backward while pulling him into your right hipThis should be the first body contact during the movement If youcontinue the pull with your hands and turn to the rear with your
left hip until you are facing in the same direction as youropponent he will be rotated over your right hip and into the mat
Since you do not want to hurt your opponent in the sport youmaintain your grip on his uniform during the fall so that he lands
on his left side and can slap the mat with his left arm duringimpact The slap spreads the impact force over a larger area sothat the stress on his ribs is not enough to hurt him Part of the
early training in judo involves timing the slap on the mat tocoincide with the impact The only time I have been hurt in thesport is when I failed to slap properly
Timing and smooth execution are essential to the hip throw but
an understanding of the physics particularly of the torques andthe center of the mass is also necessary Your opponentrsquos center
of mass is the geometric center of his mass distribution It can be
Black SpeedNunchaku $1495And
see the rest ofourNunchaku
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 38
regarded as the point where the gravitational force acts on thebody as a whole which is why it is sometimes called the center of gravity Your opponent is stable as long as his center of massremains over the support area outlined by his feet When he
stands upright in a normal posture his center of mass isapproximately between his spine and his navel Therefore he is
stable until you force or trick him into moving his center of mass
or into losing part of his support area
Suppose during a throw you manageto move your opponentrsquos center of
mass forward of his feet Even if youthen no longer aid the throw thegravitational pull on his center of mass creates a torque that might
make him fall To calculate a torqueone must multiply two items theforce acting to bring about a rotationand the lever arm between the pivot
point and the force The lever arm isthe perpendicular line from the pivot
point to a straight line through theforce If you have made your
opponent unstable the force thatcan rotate him about his feet to the
mat is the gravitational pull on himI represent this force which is merely his weight by a vectorgoing straight down from his center of mass Here the lever armis the horizontal distance between the pivot point at his feet andan extension of a vertical line running through the weight vectorThe torque on an unstable opponent is the product of his weight
and the lever arm When your opponent is upright the lever armfor his weight vector is zero and so the torque is zero too Whenhe is caught with the center of his mass forward of his feet the
lever arm is no longer zero and the resulting torque causes his
rotation The longer the lever arm (the more he is leaning) thegreater the torque
One of the objectives of judo is to trick your opponent into an
unstable position so quickly that recovery is impossible Once he
is unstable you can continue the throw by applying anothertorque to him one that will bring him to the mat long before hecan even attempt to regain his stability
During the hip throw you initially pull on your opponentrsquos uniform
to make him unstable If you pull directly toward you you will noteasily cause this instability because his center of mass would bemoved over his forward foot He could then maintain his balanceby bending that knee To make him unstable you have to move
his center of mass a relatively great distance until it is beyond hisforward foot The motion requires a strong and prolonged pullwhich he (the opponent) can counter quickly
An instability due to theweight vector
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832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 48
An easier way to make youropponent unstable is for you to pullto your right because in thatdirection his center of mass must be
displaced only a relatively shortdistance before it no longer lies over
the support area He will probably be
unable to counter such a pull beforethe instability is establishedThereafter he will not be able to
counter the continued rotationinvolved in the hip throw
Your pull has an additional purposeIt curves your opponentrsquos body so
that his center of mass is broughtforward to his navel or just outside his body This new positionwill aid you in rotating his body over your right hip Once bodycontact is made a new pivot point is established at your hip and
your pull creates a new torque on the opponent one that willcause the rotation over your hip
As mentioned above the torque is calculated by multiplying theforce on the opponent by the lever arm between the line of that
force and the pivot point This time the force is your pull and thepivot point is your hip Thus the hip throw gives rise to twotorques on your opponent one torque due to his own weight andunstable position and one due directly to your pull you are
exerting on him The throw begins with the first torque so thatyou can set up the second one without resistance from him
Suppose you do not curve your opponentrsquos body forward andbring his center of mass out to his navel Then when you attempt
to rotate his body over your right hip a torque due to his weight
will actually counter the torque from your pull on his uniformSuppose he is still in an upright position when you make the bodycontact and attempt to rotate him over your hip The pivot pointfor the rotation is your hip I shall apply it in determining thelever arms for both the torques then acting on the opponent
One of the torques is the product of your pull and the lever arm fromyour hip to the line passing through
the vector of the pull The othertorque is the product of youropponentrsquos weight and the lever armfrom your hip to a vertical linepassing through the opponentrsquos
center of mass
If your opponent is standing uprightthe torque from his weight opposesthe torque you are applying since it
attempts to rotate him in the
opposite direction over your hip Tofinish the throw you now must
overcome the torque due to his weight but the time requireddestroys your advantage in the surprise of the throw Moreoveryou must pit your strength against his
When the hip throw is properly executed you bring youropponentrsquos body forward in a curve move his center of mass out
to his navel and so decrease or eliminate the lever armassociated with his weight The torque due to his weight istherefore diminished and you have a comparatively easy time
The forces in a hip throw
An improper hip throw
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 58
rotating his body over your right hip The throw works better onan opponent who is taller than you are because you can pull himdownward into the proper curved posture more easily than youcan an opponent who is your height or shorter You can also more
easily slide your right hip under a taller opponent The lever armof your pull on the uniform of a taller opponent will also belonger thereby providing more torque to bring him over your hip
The Major Outer Reaping Throw
The ldquomajor outer reaping throwrdquo (itis called o-soto-gari in Japanese) is
somewhat easier to understand interms of the rotational motions Asyour opponent steps backward withhis left foot you step with your leftfoot just to the outside of his right
foot and pull downward on thatfoot Your pull will also be toward
his right rear so that his body is
curved backward He is already inan unstable position because your
pull moves his center of mass to hisright rear and away from thesupport area of his feet He cannotescape by sliding his feet to therear and regaining his balancebecause you have forced him
downward His instability resultsfrom the torque his weight createsaround a pivot point at his feet
primarily his right foot
The major outer reapingthrow
The lever arm runs between the
pivot point and a line through hisweight vector Placing him in this
position sets him up for the nextpart of the throw in which youfurther remove his support area andapply a second torque to bring himrapidly to the mat
You continue the throw by steppingwith your right foot around andbehind your opponentrsquos right foot
Then you sweep your opponentrsquos hipand leg to your rear while you forcehis right side downward and to the
rear leaving him with virtually nosupport base
The two torques cause him to rotate about a pivot point on yourright leg Even if you did not continue to pull on him aftersweeping his leg he would rotate about your leg because his
center of mass is being pulled down by gravity Your downwardpull provides another torque to hasten his fall In this throw thetwo torques complement each other
The Sweeping Ankle Throw
The forces in the throw
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 68
The ldquosweeping ankle throwrdquo (okuri-ashi-barai) removes youropponentrsquos leg support in a similar
manner As he is about to place hisweight on his right foot in thecourse of a step forward orbackward you sweep your left footinto that leg just above the ankle
Simultaneously you pull his uniform
in the original direction of histravel Suppose he was movingforward You pull forward (and someet no resistance from him) asyou sweep his right foot into his left
one Even if he manages to keephis left foot on the mat his supportarea is greatly reduced and isswept from under his center
His weight vector through thecenter of mass provides a torquethat will take him to the mat If youlower your body while maintaining
your pull on his uniform you willprovide another torque that willrotate him to the floor The pivot
point is his left foot and again thetwo torques complement eachother
The ankle Sweep
Mat Techniques
How to execute a cross armlock
Judo classes also teach methods of disabling an opponent on the
mat Most of these ldquohold downsrdquo entail trapping your opponent onthe mat with your weight positioned in such a way that he (theopponent) cannot roll over or rise even if he is stronger than you
are For example in the ldquocross armlockrdquo (juji-gatame) your arepositioned with part of your weight on the upper torso of your
opponent on the mat He not only is prevented from rising butalso probably will not even move for fear of having his armbroken
The maneuver originates when you are astride your opponent
who is on his back When he raises his left arm to ward you offyou grasp his right with both of your hands fall to his left side
throw your right leg across his neck and with your left kneeraised drive your left ankle into his side His left arm is pinnedbetween you legs with the elbow downward Even a gentledownward pull on his wrist creates tremendous torque on his armaround the pivot point where that arm crosses your right leg Hecannot sit up because your weight creates an overwhelming
torque on him as he attempts to rotate his trunk about a pivot
point at his hips He cannot free his left arm even if he isconsiderably stronger than you are He could try to counter your
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 78
torque on his arm by using his shoulder muscles but they wouldpull on his arm at approximately the location of the pivot pointand so their pull would have a short lever As in most judotechniques a person trained in creating the correct torques on an
opponent has a tremendous advantage even if the opponent ismuch stronger
In the second article in this two-part series we will examine theapplication of the physics of force to another combat systemaikido
Article copy2002 Jearl WalkerArtwork copy2002 Michael Goodman
Acknowledgements
This article has been edited for clarity This article and the following one inthis series ldquoThe Application Of The Physics Of Forces in Aikidordquo originallyappeared the Scientific American in the July 1980 issue under to column ldquoThe Amateur Scientistrdquo It is reproduced with the consent of ScientificAmerican and the author Jearl Walker We would also like to thankMichael Goodman for the many illustrations that also appeared in theoriginal article as well as Oscar Ratti for his contribution of the first
illustration in this article
Rate This Article
Select yourRating
Your Comments
(Please add your name or initials)
Your email address (Required)
(Check here if you would like to
receive our newsletter)
832019 Pysis Judo
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Submit About the Author
Jearl Walker studied tae-kwon-do in high school but had to give itup to survive college After earning a PhD in physics he began touse karate in his physics classes at Cleveland State Universitywhere he is a professor
He published on the physics of karate strikes in 1975 in the
AmericanJournal of Physics The article reprinted here was one of hismonthlyAmateur Scientist articles from his 13 years of writing forScientific American It is reprinted with permission
To find more articles of interest search on one of these keywords
Judo physics of judo judo throws judo matwork leveragehip throw major outer reaping throw o-soto-gariosotogari sweeping ankle throw Okuri-ashi-barai crossarmlock juji-gatame hold downs
Searc Go Read more articles by Jearl Walker
Return to Judo
Return to the Main Reading Room
Advertising Information bull FeedbackHome bull Forums bull Reading Room bull Estore bull About Us bull
Copyright copy 2000-2011 FightingArtscom a division of eCommunities LLCAll rights reserved Use of this website is governed by the Terms of Use
Privacy Statement
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 28
t
against his A small but skilled budo player has a distinctadvantage over a larger but unskilled opponent if the contest of strength is avoided
The Basic Hip Throw
The basic hip throw in Judo
Probably the best example of thisadvantage is the basic hip throwwhich is most effective against ataller and slower opponent In thenormal judo competition you faceyour opponent with your hands
grasping the lapels or shoulders of his uniform To execute the throwyou step forward with your rightfoot to a point in between his feetpulling him downward and toward
your right The throw works well if you have caught your opponent
just as he has stepped forward with
his right foot He is still stableagainst a pull directly toward you
but is considerably less stableagainst a pull to your right becauseof the position of his feet
The footwork in the hip throw
During your step forward you curve your body forward so that
your head is at your opponentrsquos shoulder level Next you rapidlyturn your left hip backward while pulling him into your right hipThis should be the first body contact during the movement If youcontinue the pull with your hands and turn to the rear with your
left hip until you are facing in the same direction as youropponent he will be rotated over your right hip and into the mat
Since you do not want to hurt your opponent in the sport youmaintain your grip on his uniform during the fall so that he lands
on his left side and can slap the mat with his left arm duringimpact The slap spreads the impact force over a larger area sothat the stress on his ribs is not enough to hurt him Part of the
early training in judo involves timing the slap on the mat tocoincide with the impact The only time I have been hurt in thesport is when I failed to slap properly
Timing and smooth execution are essential to the hip throw but
an understanding of the physics particularly of the torques andthe center of the mass is also necessary Your opponentrsquos center
of mass is the geometric center of his mass distribution It can be
Black SpeedNunchaku $1495And
see the rest ofourNunchaku
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 38
regarded as the point where the gravitational force acts on thebody as a whole which is why it is sometimes called the center of gravity Your opponent is stable as long as his center of massremains over the support area outlined by his feet When he
stands upright in a normal posture his center of mass isapproximately between his spine and his navel Therefore he is
stable until you force or trick him into moving his center of mass
or into losing part of his support area
Suppose during a throw you manageto move your opponentrsquos center of
mass forward of his feet Even if youthen no longer aid the throw thegravitational pull on his center of mass creates a torque that might
make him fall To calculate a torqueone must multiply two items theforce acting to bring about a rotationand the lever arm between the pivot
point and the force The lever arm isthe perpendicular line from the pivot
point to a straight line through theforce If you have made your
opponent unstable the force thatcan rotate him about his feet to the
mat is the gravitational pull on himI represent this force which is merely his weight by a vectorgoing straight down from his center of mass Here the lever armis the horizontal distance between the pivot point at his feet andan extension of a vertical line running through the weight vectorThe torque on an unstable opponent is the product of his weight
and the lever arm When your opponent is upright the lever armfor his weight vector is zero and so the torque is zero too Whenhe is caught with the center of his mass forward of his feet the
lever arm is no longer zero and the resulting torque causes his
rotation The longer the lever arm (the more he is leaning) thegreater the torque
One of the objectives of judo is to trick your opponent into an
unstable position so quickly that recovery is impossible Once he
is unstable you can continue the throw by applying anothertorque to him one that will bring him to the mat long before hecan even attempt to regain his stability
During the hip throw you initially pull on your opponentrsquos uniform
to make him unstable If you pull directly toward you you will noteasily cause this instability because his center of mass would bemoved over his forward foot He could then maintain his balanceby bending that knee To make him unstable you have to move
his center of mass a relatively great distance until it is beyond hisforward foot The motion requires a strong and prolonged pullwhich he (the opponent) can counter quickly
An instability due to theweight vector
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ViewsMonthlyOnly $89Details
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footage and street
fights captured withthe worlds firstbouncer spy cam
How toMatrix
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Learn entire arts foras little as $10 per
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832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 48
An easier way to make youropponent unstable is for you to pullto your right because in thatdirection his center of mass must be
displaced only a relatively shortdistance before it no longer lies over
the support area He will probably be
unable to counter such a pull beforethe instability is establishedThereafter he will not be able to
counter the continued rotationinvolved in the hip throw
Your pull has an additional purposeIt curves your opponentrsquos body so
that his center of mass is broughtforward to his navel or just outside his body This new positionwill aid you in rotating his body over your right hip Once bodycontact is made a new pivot point is established at your hip and
your pull creates a new torque on the opponent one that willcause the rotation over your hip
As mentioned above the torque is calculated by multiplying theforce on the opponent by the lever arm between the line of that
force and the pivot point This time the force is your pull and thepivot point is your hip Thus the hip throw gives rise to twotorques on your opponent one torque due to his own weight andunstable position and one due directly to your pull you are
exerting on him The throw begins with the first torque so thatyou can set up the second one without resistance from him
Suppose you do not curve your opponentrsquos body forward andbring his center of mass out to his navel Then when you attempt
to rotate his body over your right hip a torque due to his weight
will actually counter the torque from your pull on his uniformSuppose he is still in an upright position when you make the bodycontact and attempt to rotate him over your hip The pivot pointfor the rotation is your hip I shall apply it in determining thelever arms for both the torques then acting on the opponent
One of the torques is the product of your pull and the lever arm fromyour hip to the line passing through
the vector of the pull The othertorque is the product of youropponentrsquos weight and the lever armfrom your hip to a vertical linepassing through the opponentrsquos
center of mass
If your opponent is standing uprightthe torque from his weight opposesthe torque you are applying since it
attempts to rotate him in the
opposite direction over your hip Tofinish the throw you now must
overcome the torque due to his weight but the time requireddestroys your advantage in the surprise of the throw Moreoveryou must pit your strength against his
When the hip throw is properly executed you bring youropponentrsquos body forward in a curve move his center of mass out
to his navel and so decrease or eliminate the lever armassociated with his weight The torque due to his weight istherefore diminished and you have a comparatively easy time
The forces in a hip throw
An improper hip throw
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 58
rotating his body over your right hip The throw works better onan opponent who is taller than you are because you can pull himdownward into the proper curved posture more easily than youcan an opponent who is your height or shorter You can also more
easily slide your right hip under a taller opponent The lever armof your pull on the uniform of a taller opponent will also belonger thereby providing more torque to bring him over your hip
The Major Outer Reaping Throw
The ldquomajor outer reaping throwrdquo (itis called o-soto-gari in Japanese) is
somewhat easier to understand interms of the rotational motions Asyour opponent steps backward withhis left foot you step with your leftfoot just to the outside of his right
foot and pull downward on thatfoot Your pull will also be toward
his right rear so that his body is
curved backward He is already inan unstable position because your
pull moves his center of mass to hisright rear and away from thesupport area of his feet He cannotescape by sliding his feet to therear and regaining his balancebecause you have forced him
downward His instability resultsfrom the torque his weight createsaround a pivot point at his feet
primarily his right foot
The major outer reapingthrow
The lever arm runs between the
pivot point and a line through hisweight vector Placing him in this
position sets him up for the nextpart of the throw in which youfurther remove his support area andapply a second torque to bring himrapidly to the mat
You continue the throw by steppingwith your right foot around andbehind your opponentrsquos right foot
Then you sweep your opponentrsquos hipand leg to your rear while you forcehis right side downward and to the
rear leaving him with virtually nosupport base
The two torques cause him to rotate about a pivot point on yourright leg Even if you did not continue to pull on him aftersweeping his leg he would rotate about your leg because his
center of mass is being pulled down by gravity Your downwardpull provides another torque to hasten his fall In this throw thetwo torques complement each other
The Sweeping Ankle Throw
The forces in the throw
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 68
The ldquosweeping ankle throwrdquo (okuri-ashi-barai) removes youropponentrsquos leg support in a similar
manner As he is about to place hisweight on his right foot in thecourse of a step forward orbackward you sweep your left footinto that leg just above the ankle
Simultaneously you pull his uniform
in the original direction of histravel Suppose he was movingforward You pull forward (and someet no resistance from him) asyou sweep his right foot into his left
one Even if he manages to keephis left foot on the mat his supportarea is greatly reduced and isswept from under his center
His weight vector through thecenter of mass provides a torquethat will take him to the mat If youlower your body while maintaining
your pull on his uniform you willprovide another torque that willrotate him to the floor The pivot
point is his left foot and again thetwo torques complement eachother
The ankle Sweep
Mat Techniques
How to execute a cross armlock
Judo classes also teach methods of disabling an opponent on the
mat Most of these ldquohold downsrdquo entail trapping your opponent onthe mat with your weight positioned in such a way that he (theopponent) cannot roll over or rise even if he is stronger than you
are For example in the ldquocross armlockrdquo (juji-gatame) your arepositioned with part of your weight on the upper torso of your
opponent on the mat He not only is prevented from rising butalso probably will not even move for fear of having his armbroken
The maneuver originates when you are astride your opponent
who is on his back When he raises his left arm to ward you offyou grasp his right with both of your hands fall to his left side
throw your right leg across his neck and with your left kneeraised drive your left ankle into his side His left arm is pinnedbetween you legs with the elbow downward Even a gentledownward pull on his wrist creates tremendous torque on his armaround the pivot point where that arm crosses your right leg Hecannot sit up because your weight creates an overwhelming
torque on him as he attempts to rotate his trunk about a pivot
point at his hips He cannot free his left arm even if he isconsiderably stronger than you are He could try to counter your
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 78
torque on his arm by using his shoulder muscles but they wouldpull on his arm at approximately the location of the pivot pointand so their pull would have a short lever As in most judotechniques a person trained in creating the correct torques on an
opponent has a tremendous advantage even if the opponent ismuch stronger
In the second article in this two-part series we will examine theapplication of the physics of force to another combat systemaikido
Article copy2002 Jearl WalkerArtwork copy2002 Michael Goodman
Acknowledgements
This article has been edited for clarity This article and the following one inthis series ldquoThe Application Of The Physics Of Forces in Aikidordquo originallyappeared the Scientific American in the July 1980 issue under to column ldquoThe Amateur Scientistrdquo It is reproduced with the consent of ScientificAmerican and the author Jearl Walker We would also like to thankMichael Goodman for the many illustrations that also appeared in theoriginal article as well as Oscar Ratti for his contribution of the first
illustration in this article
Rate This Article
Select yourRating
Your Comments
(Please add your name or initials)
Your email address (Required)
(Check here if you would like to
receive our newsletter)
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 88
Submit About the Author
Jearl Walker studied tae-kwon-do in high school but had to give itup to survive college After earning a PhD in physics he began touse karate in his physics classes at Cleveland State Universitywhere he is a professor
He published on the physics of karate strikes in 1975 in the
AmericanJournal of Physics The article reprinted here was one of hismonthlyAmateur Scientist articles from his 13 years of writing forScientific American It is reprinted with permission
To find more articles of interest search on one of these keywords
Judo physics of judo judo throws judo matwork leveragehip throw major outer reaping throw o-soto-gariosotogari sweeping ankle throw Okuri-ashi-barai crossarmlock juji-gatame hold downs
Searc Go Read more articles by Jearl Walker
Return to Judo
Return to the Main Reading Room
Advertising Information bull FeedbackHome bull Forums bull Reading Room bull Estore bull About Us bull
Copyright copy 2000-2011 FightingArtscom a division of eCommunities LLCAll rights reserved Use of this website is governed by the Terms of Use
Privacy Statement
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 38
regarded as the point where the gravitational force acts on thebody as a whole which is why it is sometimes called the center of gravity Your opponent is stable as long as his center of massremains over the support area outlined by his feet When he
stands upright in a normal posture his center of mass isapproximately between his spine and his navel Therefore he is
stable until you force or trick him into moving his center of mass
or into losing part of his support area
Suppose during a throw you manageto move your opponentrsquos center of
mass forward of his feet Even if youthen no longer aid the throw thegravitational pull on his center of mass creates a torque that might
make him fall To calculate a torqueone must multiply two items theforce acting to bring about a rotationand the lever arm between the pivot
point and the force The lever arm isthe perpendicular line from the pivot
point to a straight line through theforce If you have made your
opponent unstable the force thatcan rotate him about his feet to the
mat is the gravitational pull on himI represent this force which is merely his weight by a vectorgoing straight down from his center of mass Here the lever armis the horizontal distance between the pivot point at his feet andan extension of a vertical line running through the weight vectorThe torque on an unstable opponent is the product of his weight
and the lever arm When your opponent is upright the lever armfor his weight vector is zero and so the torque is zero too Whenhe is caught with the center of his mass forward of his feet the
lever arm is no longer zero and the resulting torque causes his
rotation The longer the lever arm (the more he is leaning) thegreater the torque
One of the objectives of judo is to trick your opponent into an
unstable position so quickly that recovery is impossible Once he
is unstable you can continue the throw by applying anothertorque to him one that will bring him to the mat long before hecan even attempt to regain his stability
During the hip throw you initially pull on your opponentrsquos uniform
to make him unstable If you pull directly toward you you will noteasily cause this instability because his center of mass would bemoved over his forward foot He could then maintain his balanceby bending that knee To make him unstable you have to move
his center of mass a relatively great distance until it is beyond hisforward foot The motion requires a strong and prolonged pullwhich he (the opponent) can counter quickly
An instability due to theweight vector
Action Ads15 MillionPlus Page
ViewsMonthlyOnly $89Details
Fight Videos Night club fight
footage and street
fights captured withthe worlds firstbouncer spy cam
How toMatrix
Learn ten timesfaster with newtraining method
Learn entire arts foras little as $10 per
disk
Self Defense Stun guns pepper
spray Mace andself defenseproducts Alarmsfor personal and
home use
TASERMC26C
Stop An UrbanGorilla Get 2 FREE
TASER M26CReplacement AirCartridges With
Each New TASERM26C
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 48
An easier way to make youropponent unstable is for you to pullto your right because in thatdirection his center of mass must be
displaced only a relatively shortdistance before it no longer lies over
the support area He will probably be
unable to counter such a pull beforethe instability is establishedThereafter he will not be able to
counter the continued rotationinvolved in the hip throw
Your pull has an additional purposeIt curves your opponentrsquos body so
that his center of mass is broughtforward to his navel or just outside his body This new positionwill aid you in rotating his body over your right hip Once bodycontact is made a new pivot point is established at your hip and
your pull creates a new torque on the opponent one that willcause the rotation over your hip
As mentioned above the torque is calculated by multiplying theforce on the opponent by the lever arm between the line of that
force and the pivot point This time the force is your pull and thepivot point is your hip Thus the hip throw gives rise to twotorques on your opponent one torque due to his own weight andunstable position and one due directly to your pull you are
exerting on him The throw begins with the first torque so thatyou can set up the second one without resistance from him
Suppose you do not curve your opponentrsquos body forward andbring his center of mass out to his navel Then when you attempt
to rotate his body over your right hip a torque due to his weight
will actually counter the torque from your pull on his uniformSuppose he is still in an upright position when you make the bodycontact and attempt to rotate him over your hip The pivot pointfor the rotation is your hip I shall apply it in determining thelever arms for both the torques then acting on the opponent
One of the torques is the product of your pull and the lever arm fromyour hip to the line passing through
the vector of the pull The othertorque is the product of youropponentrsquos weight and the lever armfrom your hip to a vertical linepassing through the opponentrsquos
center of mass
If your opponent is standing uprightthe torque from his weight opposesthe torque you are applying since it
attempts to rotate him in the
opposite direction over your hip Tofinish the throw you now must
overcome the torque due to his weight but the time requireddestroys your advantage in the surprise of the throw Moreoveryou must pit your strength against his
When the hip throw is properly executed you bring youropponentrsquos body forward in a curve move his center of mass out
to his navel and so decrease or eliminate the lever armassociated with his weight The torque due to his weight istherefore diminished and you have a comparatively easy time
The forces in a hip throw
An improper hip throw
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 58
rotating his body over your right hip The throw works better onan opponent who is taller than you are because you can pull himdownward into the proper curved posture more easily than youcan an opponent who is your height or shorter You can also more
easily slide your right hip under a taller opponent The lever armof your pull on the uniform of a taller opponent will also belonger thereby providing more torque to bring him over your hip
The Major Outer Reaping Throw
The ldquomajor outer reaping throwrdquo (itis called o-soto-gari in Japanese) is
somewhat easier to understand interms of the rotational motions Asyour opponent steps backward withhis left foot you step with your leftfoot just to the outside of his right
foot and pull downward on thatfoot Your pull will also be toward
his right rear so that his body is
curved backward He is already inan unstable position because your
pull moves his center of mass to hisright rear and away from thesupport area of his feet He cannotescape by sliding his feet to therear and regaining his balancebecause you have forced him
downward His instability resultsfrom the torque his weight createsaround a pivot point at his feet
primarily his right foot
The major outer reapingthrow
The lever arm runs between the
pivot point and a line through hisweight vector Placing him in this
position sets him up for the nextpart of the throw in which youfurther remove his support area andapply a second torque to bring himrapidly to the mat
You continue the throw by steppingwith your right foot around andbehind your opponentrsquos right foot
Then you sweep your opponentrsquos hipand leg to your rear while you forcehis right side downward and to the
rear leaving him with virtually nosupport base
The two torques cause him to rotate about a pivot point on yourright leg Even if you did not continue to pull on him aftersweeping his leg he would rotate about your leg because his
center of mass is being pulled down by gravity Your downwardpull provides another torque to hasten his fall In this throw thetwo torques complement each other
The Sweeping Ankle Throw
The forces in the throw
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 68
The ldquosweeping ankle throwrdquo (okuri-ashi-barai) removes youropponentrsquos leg support in a similar
manner As he is about to place hisweight on his right foot in thecourse of a step forward orbackward you sweep your left footinto that leg just above the ankle
Simultaneously you pull his uniform
in the original direction of histravel Suppose he was movingforward You pull forward (and someet no resistance from him) asyou sweep his right foot into his left
one Even if he manages to keephis left foot on the mat his supportarea is greatly reduced and isswept from under his center
His weight vector through thecenter of mass provides a torquethat will take him to the mat If youlower your body while maintaining
your pull on his uniform you willprovide another torque that willrotate him to the floor The pivot
point is his left foot and again thetwo torques complement eachother
The ankle Sweep
Mat Techniques
How to execute a cross armlock
Judo classes also teach methods of disabling an opponent on the
mat Most of these ldquohold downsrdquo entail trapping your opponent onthe mat with your weight positioned in such a way that he (theopponent) cannot roll over or rise even if he is stronger than you
are For example in the ldquocross armlockrdquo (juji-gatame) your arepositioned with part of your weight on the upper torso of your
opponent on the mat He not only is prevented from rising butalso probably will not even move for fear of having his armbroken
The maneuver originates when you are astride your opponent
who is on his back When he raises his left arm to ward you offyou grasp his right with both of your hands fall to his left side
throw your right leg across his neck and with your left kneeraised drive your left ankle into his side His left arm is pinnedbetween you legs with the elbow downward Even a gentledownward pull on his wrist creates tremendous torque on his armaround the pivot point where that arm crosses your right leg Hecannot sit up because your weight creates an overwhelming
torque on him as he attempts to rotate his trunk about a pivot
point at his hips He cannot free his left arm even if he isconsiderably stronger than you are He could try to counter your
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 78
torque on his arm by using his shoulder muscles but they wouldpull on his arm at approximately the location of the pivot pointand so their pull would have a short lever As in most judotechniques a person trained in creating the correct torques on an
opponent has a tremendous advantage even if the opponent ismuch stronger
In the second article in this two-part series we will examine theapplication of the physics of force to another combat systemaikido
Article copy2002 Jearl WalkerArtwork copy2002 Michael Goodman
Acknowledgements
This article has been edited for clarity This article and the following one inthis series ldquoThe Application Of The Physics Of Forces in Aikidordquo originallyappeared the Scientific American in the July 1980 issue under to column ldquoThe Amateur Scientistrdquo It is reproduced with the consent of ScientificAmerican and the author Jearl Walker We would also like to thankMichael Goodman for the many illustrations that also appeared in theoriginal article as well as Oscar Ratti for his contribution of the first
illustration in this article
Rate This Article
Select yourRating
Your Comments
(Please add your name or initials)
Your email address (Required)
(Check here if you would like to
receive our newsletter)
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 88
Submit About the Author
Jearl Walker studied tae-kwon-do in high school but had to give itup to survive college After earning a PhD in physics he began touse karate in his physics classes at Cleveland State Universitywhere he is a professor
He published on the physics of karate strikes in 1975 in the
AmericanJournal of Physics The article reprinted here was one of hismonthlyAmateur Scientist articles from his 13 years of writing forScientific American It is reprinted with permission
To find more articles of interest search on one of these keywords
Judo physics of judo judo throws judo matwork leveragehip throw major outer reaping throw o-soto-gariosotogari sweeping ankle throw Okuri-ashi-barai crossarmlock juji-gatame hold downs
Searc Go Read more articles by Jearl Walker
Return to Judo
Return to the Main Reading Room
Advertising Information bull FeedbackHome bull Forums bull Reading Room bull Estore bull About Us bull
Copyright copy 2000-2011 FightingArtscom a division of eCommunities LLCAll rights reserved Use of this website is governed by the Terms of Use
Privacy Statement
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 48
An easier way to make youropponent unstable is for you to pullto your right because in thatdirection his center of mass must be
displaced only a relatively shortdistance before it no longer lies over
the support area He will probably be
unable to counter such a pull beforethe instability is establishedThereafter he will not be able to
counter the continued rotationinvolved in the hip throw
Your pull has an additional purposeIt curves your opponentrsquos body so
that his center of mass is broughtforward to his navel or just outside his body This new positionwill aid you in rotating his body over your right hip Once bodycontact is made a new pivot point is established at your hip and
your pull creates a new torque on the opponent one that willcause the rotation over your hip
As mentioned above the torque is calculated by multiplying theforce on the opponent by the lever arm between the line of that
force and the pivot point This time the force is your pull and thepivot point is your hip Thus the hip throw gives rise to twotorques on your opponent one torque due to his own weight andunstable position and one due directly to your pull you are
exerting on him The throw begins with the first torque so thatyou can set up the second one without resistance from him
Suppose you do not curve your opponentrsquos body forward andbring his center of mass out to his navel Then when you attempt
to rotate his body over your right hip a torque due to his weight
will actually counter the torque from your pull on his uniformSuppose he is still in an upright position when you make the bodycontact and attempt to rotate him over your hip The pivot pointfor the rotation is your hip I shall apply it in determining thelever arms for both the torques then acting on the opponent
One of the torques is the product of your pull and the lever arm fromyour hip to the line passing through
the vector of the pull The othertorque is the product of youropponentrsquos weight and the lever armfrom your hip to a vertical linepassing through the opponentrsquos
center of mass
If your opponent is standing uprightthe torque from his weight opposesthe torque you are applying since it
attempts to rotate him in the
opposite direction over your hip Tofinish the throw you now must
overcome the torque due to his weight but the time requireddestroys your advantage in the surprise of the throw Moreoveryou must pit your strength against his
When the hip throw is properly executed you bring youropponentrsquos body forward in a curve move his center of mass out
to his navel and so decrease or eliminate the lever armassociated with his weight The torque due to his weight istherefore diminished and you have a comparatively easy time
The forces in a hip throw
An improper hip throw
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 58
rotating his body over your right hip The throw works better onan opponent who is taller than you are because you can pull himdownward into the proper curved posture more easily than youcan an opponent who is your height or shorter You can also more
easily slide your right hip under a taller opponent The lever armof your pull on the uniform of a taller opponent will also belonger thereby providing more torque to bring him over your hip
The Major Outer Reaping Throw
The ldquomajor outer reaping throwrdquo (itis called o-soto-gari in Japanese) is
somewhat easier to understand interms of the rotational motions Asyour opponent steps backward withhis left foot you step with your leftfoot just to the outside of his right
foot and pull downward on thatfoot Your pull will also be toward
his right rear so that his body is
curved backward He is already inan unstable position because your
pull moves his center of mass to hisright rear and away from thesupport area of his feet He cannotescape by sliding his feet to therear and regaining his balancebecause you have forced him
downward His instability resultsfrom the torque his weight createsaround a pivot point at his feet
primarily his right foot
The major outer reapingthrow
The lever arm runs between the
pivot point and a line through hisweight vector Placing him in this
position sets him up for the nextpart of the throw in which youfurther remove his support area andapply a second torque to bring himrapidly to the mat
You continue the throw by steppingwith your right foot around andbehind your opponentrsquos right foot
Then you sweep your opponentrsquos hipand leg to your rear while you forcehis right side downward and to the
rear leaving him with virtually nosupport base
The two torques cause him to rotate about a pivot point on yourright leg Even if you did not continue to pull on him aftersweeping his leg he would rotate about your leg because his
center of mass is being pulled down by gravity Your downwardpull provides another torque to hasten his fall In this throw thetwo torques complement each other
The Sweeping Ankle Throw
The forces in the throw
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 68
The ldquosweeping ankle throwrdquo (okuri-ashi-barai) removes youropponentrsquos leg support in a similar
manner As he is about to place hisweight on his right foot in thecourse of a step forward orbackward you sweep your left footinto that leg just above the ankle
Simultaneously you pull his uniform
in the original direction of histravel Suppose he was movingforward You pull forward (and someet no resistance from him) asyou sweep his right foot into his left
one Even if he manages to keephis left foot on the mat his supportarea is greatly reduced and isswept from under his center
His weight vector through thecenter of mass provides a torquethat will take him to the mat If youlower your body while maintaining
your pull on his uniform you willprovide another torque that willrotate him to the floor The pivot
point is his left foot and again thetwo torques complement eachother
The ankle Sweep
Mat Techniques
How to execute a cross armlock
Judo classes also teach methods of disabling an opponent on the
mat Most of these ldquohold downsrdquo entail trapping your opponent onthe mat with your weight positioned in such a way that he (theopponent) cannot roll over or rise even if he is stronger than you
are For example in the ldquocross armlockrdquo (juji-gatame) your arepositioned with part of your weight on the upper torso of your
opponent on the mat He not only is prevented from rising butalso probably will not even move for fear of having his armbroken
The maneuver originates when you are astride your opponent
who is on his back When he raises his left arm to ward you offyou grasp his right with both of your hands fall to his left side
throw your right leg across his neck and with your left kneeraised drive your left ankle into his side His left arm is pinnedbetween you legs with the elbow downward Even a gentledownward pull on his wrist creates tremendous torque on his armaround the pivot point where that arm crosses your right leg Hecannot sit up because your weight creates an overwhelming
torque on him as he attempts to rotate his trunk about a pivot
point at his hips He cannot free his left arm even if he isconsiderably stronger than you are He could try to counter your
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 78
torque on his arm by using his shoulder muscles but they wouldpull on his arm at approximately the location of the pivot pointand so their pull would have a short lever As in most judotechniques a person trained in creating the correct torques on an
opponent has a tremendous advantage even if the opponent ismuch stronger
In the second article in this two-part series we will examine theapplication of the physics of force to another combat systemaikido
Article copy2002 Jearl WalkerArtwork copy2002 Michael Goodman
Acknowledgements
This article has been edited for clarity This article and the following one inthis series ldquoThe Application Of The Physics Of Forces in Aikidordquo originallyappeared the Scientific American in the July 1980 issue under to column ldquoThe Amateur Scientistrdquo It is reproduced with the consent of ScientificAmerican and the author Jearl Walker We would also like to thankMichael Goodman for the many illustrations that also appeared in theoriginal article as well as Oscar Ratti for his contribution of the first
illustration in this article
Rate This Article
Select yourRating
Your Comments
(Please add your name or initials)
Your email address (Required)
(Check here if you would like to
receive our newsletter)
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 88
Submit About the Author
Jearl Walker studied tae-kwon-do in high school but had to give itup to survive college After earning a PhD in physics he began touse karate in his physics classes at Cleveland State Universitywhere he is a professor
He published on the physics of karate strikes in 1975 in the
AmericanJournal of Physics The article reprinted here was one of hismonthlyAmateur Scientist articles from his 13 years of writing forScientific American It is reprinted with permission
To find more articles of interest search on one of these keywords
Judo physics of judo judo throws judo matwork leveragehip throw major outer reaping throw o-soto-gariosotogari sweeping ankle throw Okuri-ashi-barai crossarmlock juji-gatame hold downs
Searc Go Read more articles by Jearl Walker
Return to Judo
Return to the Main Reading Room
Advertising Information bull FeedbackHome bull Forums bull Reading Room bull Estore bull About Us bull
Copyright copy 2000-2011 FightingArtscom a division of eCommunities LLCAll rights reserved Use of this website is governed by the Terms of Use
Privacy Statement
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 58
rotating his body over your right hip The throw works better onan opponent who is taller than you are because you can pull himdownward into the proper curved posture more easily than youcan an opponent who is your height or shorter You can also more
easily slide your right hip under a taller opponent The lever armof your pull on the uniform of a taller opponent will also belonger thereby providing more torque to bring him over your hip
The Major Outer Reaping Throw
The ldquomajor outer reaping throwrdquo (itis called o-soto-gari in Japanese) is
somewhat easier to understand interms of the rotational motions Asyour opponent steps backward withhis left foot you step with your leftfoot just to the outside of his right
foot and pull downward on thatfoot Your pull will also be toward
his right rear so that his body is
curved backward He is already inan unstable position because your
pull moves his center of mass to hisright rear and away from thesupport area of his feet He cannotescape by sliding his feet to therear and regaining his balancebecause you have forced him
downward His instability resultsfrom the torque his weight createsaround a pivot point at his feet
primarily his right foot
The major outer reapingthrow
The lever arm runs between the
pivot point and a line through hisweight vector Placing him in this
position sets him up for the nextpart of the throw in which youfurther remove his support area andapply a second torque to bring himrapidly to the mat
You continue the throw by steppingwith your right foot around andbehind your opponentrsquos right foot
Then you sweep your opponentrsquos hipand leg to your rear while you forcehis right side downward and to the
rear leaving him with virtually nosupport base
The two torques cause him to rotate about a pivot point on yourright leg Even if you did not continue to pull on him aftersweeping his leg he would rotate about your leg because his
center of mass is being pulled down by gravity Your downwardpull provides another torque to hasten his fall In this throw thetwo torques complement each other
The Sweeping Ankle Throw
The forces in the throw
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 68
The ldquosweeping ankle throwrdquo (okuri-ashi-barai) removes youropponentrsquos leg support in a similar
manner As he is about to place hisweight on his right foot in thecourse of a step forward orbackward you sweep your left footinto that leg just above the ankle
Simultaneously you pull his uniform
in the original direction of histravel Suppose he was movingforward You pull forward (and someet no resistance from him) asyou sweep his right foot into his left
one Even if he manages to keephis left foot on the mat his supportarea is greatly reduced and isswept from under his center
His weight vector through thecenter of mass provides a torquethat will take him to the mat If youlower your body while maintaining
your pull on his uniform you willprovide another torque that willrotate him to the floor The pivot
point is his left foot and again thetwo torques complement eachother
The ankle Sweep
Mat Techniques
How to execute a cross armlock
Judo classes also teach methods of disabling an opponent on the
mat Most of these ldquohold downsrdquo entail trapping your opponent onthe mat with your weight positioned in such a way that he (theopponent) cannot roll over or rise even if he is stronger than you
are For example in the ldquocross armlockrdquo (juji-gatame) your arepositioned with part of your weight on the upper torso of your
opponent on the mat He not only is prevented from rising butalso probably will not even move for fear of having his armbroken
The maneuver originates when you are astride your opponent
who is on his back When he raises his left arm to ward you offyou grasp his right with both of your hands fall to his left side
throw your right leg across his neck and with your left kneeraised drive your left ankle into his side His left arm is pinnedbetween you legs with the elbow downward Even a gentledownward pull on his wrist creates tremendous torque on his armaround the pivot point where that arm crosses your right leg Hecannot sit up because your weight creates an overwhelming
torque on him as he attempts to rotate his trunk about a pivot
point at his hips He cannot free his left arm even if he isconsiderably stronger than you are He could try to counter your
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 78
torque on his arm by using his shoulder muscles but they wouldpull on his arm at approximately the location of the pivot pointand so their pull would have a short lever As in most judotechniques a person trained in creating the correct torques on an
opponent has a tremendous advantage even if the opponent ismuch stronger
In the second article in this two-part series we will examine theapplication of the physics of force to another combat systemaikido
Article copy2002 Jearl WalkerArtwork copy2002 Michael Goodman
Acknowledgements
This article has been edited for clarity This article and the following one inthis series ldquoThe Application Of The Physics Of Forces in Aikidordquo originallyappeared the Scientific American in the July 1980 issue under to column ldquoThe Amateur Scientistrdquo It is reproduced with the consent of ScientificAmerican and the author Jearl Walker We would also like to thankMichael Goodman for the many illustrations that also appeared in theoriginal article as well as Oscar Ratti for his contribution of the first
illustration in this article
Rate This Article
Select yourRating
Your Comments
(Please add your name or initials)
Your email address (Required)
(Check here if you would like to
receive our newsletter)
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 88
Submit About the Author
Jearl Walker studied tae-kwon-do in high school but had to give itup to survive college After earning a PhD in physics he began touse karate in his physics classes at Cleveland State Universitywhere he is a professor
He published on the physics of karate strikes in 1975 in the
AmericanJournal of Physics The article reprinted here was one of hismonthlyAmateur Scientist articles from his 13 years of writing forScientific American It is reprinted with permission
To find more articles of interest search on one of these keywords
Judo physics of judo judo throws judo matwork leveragehip throw major outer reaping throw o-soto-gariosotogari sweeping ankle throw Okuri-ashi-barai crossarmlock juji-gatame hold downs
Searc Go Read more articles by Jearl Walker
Return to Judo
Return to the Main Reading Room
Advertising Information bull FeedbackHome bull Forums bull Reading Room bull Estore bull About Us bull
Copyright copy 2000-2011 FightingArtscom a division of eCommunities LLCAll rights reserved Use of this website is governed by the Terms of Use
Privacy Statement
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 68
The ldquosweeping ankle throwrdquo (okuri-ashi-barai) removes youropponentrsquos leg support in a similar
manner As he is about to place hisweight on his right foot in thecourse of a step forward orbackward you sweep your left footinto that leg just above the ankle
Simultaneously you pull his uniform
in the original direction of histravel Suppose he was movingforward You pull forward (and someet no resistance from him) asyou sweep his right foot into his left
one Even if he manages to keephis left foot on the mat his supportarea is greatly reduced and isswept from under his center
His weight vector through thecenter of mass provides a torquethat will take him to the mat If youlower your body while maintaining
your pull on his uniform you willprovide another torque that willrotate him to the floor The pivot
point is his left foot and again thetwo torques complement eachother
The ankle Sweep
Mat Techniques
How to execute a cross armlock
Judo classes also teach methods of disabling an opponent on the
mat Most of these ldquohold downsrdquo entail trapping your opponent onthe mat with your weight positioned in such a way that he (theopponent) cannot roll over or rise even if he is stronger than you
are For example in the ldquocross armlockrdquo (juji-gatame) your arepositioned with part of your weight on the upper torso of your
opponent on the mat He not only is prevented from rising butalso probably will not even move for fear of having his armbroken
The maneuver originates when you are astride your opponent
who is on his back When he raises his left arm to ward you offyou grasp his right with both of your hands fall to his left side
throw your right leg across his neck and with your left kneeraised drive your left ankle into his side His left arm is pinnedbetween you legs with the elbow downward Even a gentledownward pull on his wrist creates tremendous torque on his armaround the pivot point where that arm crosses your right leg Hecannot sit up because your weight creates an overwhelming
torque on him as he attempts to rotate his trunk about a pivot
point at his hips He cannot free his left arm even if he isconsiderably stronger than you are He could try to counter your
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 78
torque on his arm by using his shoulder muscles but they wouldpull on his arm at approximately the location of the pivot pointand so their pull would have a short lever As in most judotechniques a person trained in creating the correct torques on an
opponent has a tremendous advantage even if the opponent ismuch stronger
In the second article in this two-part series we will examine theapplication of the physics of force to another combat systemaikido
Article copy2002 Jearl WalkerArtwork copy2002 Michael Goodman
Acknowledgements
This article has been edited for clarity This article and the following one inthis series ldquoThe Application Of The Physics Of Forces in Aikidordquo originallyappeared the Scientific American in the July 1980 issue under to column ldquoThe Amateur Scientistrdquo It is reproduced with the consent of ScientificAmerican and the author Jearl Walker We would also like to thankMichael Goodman for the many illustrations that also appeared in theoriginal article as well as Oscar Ratti for his contribution of the first
illustration in this article
Rate This Article
Select yourRating
Your Comments
(Please add your name or initials)
Your email address (Required)
(Check here if you would like to
receive our newsletter)
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 88
Submit About the Author
Jearl Walker studied tae-kwon-do in high school but had to give itup to survive college After earning a PhD in physics he began touse karate in his physics classes at Cleveland State Universitywhere he is a professor
He published on the physics of karate strikes in 1975 in the
AmericanJournal of Physics The article reprinted here was one of hismonthlyAmateur Scientist articles from his 13 years of writing forScientific American It is reprinted with permission
To find more articles of interest search on one of these keywords
Judo physics of judo judo throws judo matwork leveragehip throw major outer reaping throw o-soto-gariosotogari sweeping ankle throw Okuri-ashi-barai crossarmlock juji-gatame hold downs
Searc Go Read more articles by Jearl Walker
Return to Judo
Return to the Main Reading Room
Advertising Information bull FeedbackHome bull Forums bull Reading Room bull Estore bull About Us bull
Copyright copy 2000-2011 FightingArtscom a division of eCommunities LLCAll rights reserved Use of this website is governed by the Terms of Use
Privacy Statement
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 78
torque on his arm by using his shoulder muscles but they wouldpull on his arm at approximately the location of the pivot pointand so their pull would have a short lever As in most judotechniques a person trained in creating the correct torques on an
opponent has a tremendous advantage even if the opponent ismuch stronger
In the second article in this two-part series we will examine theapplication of the physics of force to another combat systemaikido
Article copy2002 Jearl WalkerArtwork copy2002 Michael Goodman
Acknowledgements
This article has been edited for clarity This article and the following one inthis series ldquoThe Application Of The Physics Of Forces in Aikidordquo originallyappeared the Scientific American in the July 1980 issue under to column ldquoThe Amateur Scientistrdquo It is reproduced with the consent of ScientificAmerican and the author Jearl Walker We would also like to thankMichael Goodman for the many illustrations that also appeared in theoriginal article as well as Oscar Ratti for his contribution of the first
illustration in this article
Rate This Article
Select yourRating
Your Comments
(Please add your name or initials)
Your email address (Required)
(Check here if you would like to
receive our newsletter)
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 88
Submit About the Author
Jearl Walker studied tae-kwon-do in high school but had to give itup to survive college After earning a PhD in physics he began touse karate in his physics classes at Cleveland State Universitywhere he is a professor
He published on the physics of karate strikes in 1975 in the
AmericanJournal of Physics The article reprinted here was one of hismonthlyAmateur Scientist articles from his 13 years of writing forScientific American It is reprinted with permission
To find more articles of interest search on one of these keywords
Judo physics of judo judo throws judo matwork leveragehip throw major outer reaping throw o-soto-gariosotogari sweeping ankle throw Okuri-ashi-barai crossarmlock juji-gatame hold downs
Searc Go Read more articles by Jearl Walker
Return to Judo
Return to the Main Reading Room
Advertising Information bull FeedbackHome bull Forums bull Reading Room bull Estore bull About Us bull
Copyright copy 2000-2011 FightingArtscom a division of eCommunities LLCAll rights reserved Use of this website is governed by the Terms of Use
Privacy Statement
832019 Pysis Judo
httpslidepdfcomreaderfullpysis-judo 88
Submit About the Author
Jearl Walker studied tae-kwon-do in high school but had to give itup to survive college After earning a PhD in physics he began touse karate in his physics classes at Cleveland State Universitywhere he is a professor
He published on the physics of karate strikes in 1975 in the
AmericanJournal of Physics The article reprinted here was one of hismonthlyAmateur Scientist articles from his 13 years of writing forScientific American It is reprinted with permission
To find more articles of interest search on one of these keywords
Judo physics of judo judo throws judo matwork leveragehip throw major outer reaping throw o-soto-gariosotogari sweeping ankle throw Okuri-ashi-barai crossarmlock juji-gatame hold downs
Searc Go Read more articles by Jearl Walker
Return to Judo
Return to the Main Reading Room
Advertising Information bull FeedbackHome bull Forums bull Reading Room bull Estore bull About Us bull
Copyright copy 2000-2011 FightingArtscom a division of eCommunities LLCAll rights reserved Use of this website is governed by the Terms of Use
Privacy Statement