4.1/2 Newton’s First and Second Laws
Transcript of 4.1/2 Newton’s First and Second Laws
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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