newton’s laws. 2 vectors and scalars vectors a quantity that has 2 dimensions, magnitude and...
TRANSCRIPT
Newton’s Laws
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Vectors and scalars
VectorsA quantity that has 2 dimensions,
MAGNITUDE and DIRECTIONScalars
A quantity that has a single dimension MAGNITUDE
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Vectors and scalars
Term Definition Vector or Scalar
displacement
temperature
Speed
Velocity
Distance
Acceleration
Forces
Weight
deceleration
mass
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Forces F=MA
Forces cause ; A force is a
“A force is that which alters or to alter a body’s or of in a line.”
If a body changes or , a has been applied
force
movementpush or a pull
tendsstate of rest
uniform motion straight
direction velocity
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Forces affecting motion
External Reaction forces Gravity Air resistance/friction
Internal Muscular
contractions
Vertical Weight – mass x
acceleration Gravity Air resistance/friction Reaction force
Horizontal Friction Air resistance
Impulse
Impulse = force x time
The length of time a force is applied to an object or body and therefore change in momentum
Sporting examples?
Reaction force
Reaction force always occur when 2 bodies are in contact
Act at 90 degrees to contacted surface
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Forces affecting motion
Unbalanced Where a force acting in 1
direction is larger than that acting in the opposite direction
Object or body will start to move or accelerate/decelerate in the direction of the bigger force
Balanced 2 or more forces are
of equal size but in opposite direction
All the forces cancel themselves out so zero net force
Object or body will remain stationary or remain constant in its velocity
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Ground Reaction Force
Action force of muscle contraction
Equal and opposite Ground Reaction Force
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Forces applied - runner
‘action force’ applied to ground Reaction force from between ground and foot Air resistance
Muscular
groundGravity
Friction
to forward motion
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Forces acting on a sprinter
Action force of muscular contraction
Friction
Gravity
Air resistance
Equal and opposite Ground Reaction Force
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Forces applied – high jumper
‘action force’ applied to ground
Reaction force from - large vertical component
between ground and footAir resistance
Muscular
ground
Gravity
Friction
to forward motion
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Forces applied – kicking
forces applied to ballReaction force from
between ball and footAir resistance
Muscular
ballGravity
Friction
to forward motion
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Newton’s Laws
• 1st Law –
• A body will remain in its / until affected by a
• A body has a to change its
Law of inertia
state of motion
reluctance
rest force
state of motion
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Applying Newton’s 1st Law
• Sprinter remains in on blocks until a causes him to change his
• Ball keeps moving until a causes it to change its
force
set positionforce
state of motion
state of motion
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Momentum
In sporting situations, remains constant; therefore inertia
All objects in motion have mass and
Product = Momentum = mass x velocity
mass
stays the same
velocity
momentum
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Newton’s Laws
• 2nd Law –
• The rate of change of is to the force causing the change, and the change takes place in the in which the force was applied • In sport, remains constant and therefore momentum equates to
Law of acceleration
momentumdirectly proportional
directionmass
acceleration
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Applying Newton’s 2nd Law
• The (size) and of force applied by the sprinter to the blocks determines the and of received – because mass remains constant• Acceleration is to applied•
magnitude direction
magnitude directionacceleration
proportional force
F = ma
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Newton’s Laws
• 3rd Law – Law of Reaction
• To every force there is an and reaction force
equal
opposite
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Applying Newton’s 3rd Law
The sprinter applies a to the ground. This results in a force causing movement
The sprinter cannot move the
Reaction force from ground =
muscular forcereaction
earth/blocks
Ground Reaction Force
Extended work
Tomorrow’s lesson, you will be in groups of 4.
With use of video camera and practical performer you will apply Newton’s 3 Laws of Motion to your choice of a sporting situation
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Typical question
Use Newton’s Three Laws of Motion to explain how a tennis player moves towards the ball in preparation to play a stroke. (5 marks)
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Answer
First Law – reluctance to change state of motion/constant motion/ uniform motion/velocity;Force required to change state of motion/overcome inertia of player;Muscle contractions; (Sub max 2 marks)
Second Law – magnitude/size of force governs change in momentum;Mass remains constant;Force governs magnitude of acceleration given to player;And direction; (Sub max 2 marks)
Third Law – equal and opposite reaction force;Force applied to ground/ moves performer;Ground Reaction Force. (Sub max 2 marks)
Max of 5 marksDo not credit Force = Mass x AccelerationOnly credit responses that relate to the player not the ball.