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4.1/2Newton’sFirstandSecondLaws

LearningIntentions:

Ican:

ü ExplaintheLawofInertiausingwordsü ExplainNewton’sFirstandSecondLawusingwordsü Usefreebodydiagramstosolveproblemsinvolvingforce

Imagineyouareridinginatruckwhensuddenlythedriverturnslefttoavoidapothole.Youwill

likelyfeela_____________towardsthesideofthevehicle.

Thetendencythatallobjectshaveto______________changesintheir__________________is

calledinertia.Galileonoticedthisinthe1500sandformulatedhis__________of

_______________.

Inertiadependsonmass.Themoremassthatanobjecthas,thegreaterthe__________

requiredtoalteritsmovement.

i.e.NissanMicravsSemiTruck

Newton’sFirstLawofMotion

NewtonrestatedGalileo’sLawofInertiainhis____________Lawof____________:

“Abodywillcontinuetomoveataconstantspeedandinthesamedirectionforaslongastherearenounbalancedforcesactingonit”

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Newton’sSecondLawofMotion

Sinceanobjectwillnotalteritspathunlessthereisanunbalancedforceactingonit,itmustbe

________________inthedirectionoftheforce.

Newtonrestatesthisinhis_________________Lawof_________________

“Ifanunbalancedforceactsonabody,thebodywillaccelerate.Therateatwhichitacceleratesdependsdirectlyontheunbalancedforceandinverselyonthemassofthebody”

Asanequation,Newton’sSecondLawstates: ! = #$

Or,asitisusuallystated:

Example:

ACessnaplanehasamassof1500kgandhasamaximumaccelerationof0.40&'(.Whatisthe

unbalancedforceontheplane?

Example:

Whatisthemassofatorpedothatacceleratesatarateof2.0&'(andhasanetforceof25000N?

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OnyourOwn:

Findtheaccelerationofapassengerjetthathasamassof250,000kgandprovidesan

unbalancedforceof50,000N

FreeBodyDiagrams:

Whenthereare______________than______________actingonabody,weneedtofigure

outwhatthe__________forceactingontheobjectis.Todothis,wedrawaFreeBodyDiagram

Afterplacingtheforcesintherightdirection,addorsubtractallforcesactinginthesameplane

(i.e.up/down,forward/back)andtheresultingforceisthe_______force.

Example:

Victoriastepsoutsideonaparticularlywindyday.Shecreatesaforceof40Nforwards,butshe

experiencesaheadwindof5N.Shealsoispushedleftbythewindwithaforceof16Nandright

withaforceof26N.FindthenetforceactingonVictoria.

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Example:

Anetforceof20Nisactingonafallingobject.Theobjectexperiencesairresistanceof6.0N.If

accelerationduetogravityis9.8&'(whatisthemassoftheobject?

Example:

Aforceof50Nacceleratesa5.0kgblockat6.0&'(alongahorizontalsurface.

a) Whatisthefrictionalforceactingontheblock?

b) WhatisthecoefficientofFriction?

Assignment: P.108#3-7

P.115#1-5