Ch 9 Notes. Momentum: inertia in motion ρ = m v ρ (rho) units of kgm/s VECTOR QUANTITY Inertia of...

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Momentum Introduction Ch 9 Notes
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Transcript of Ch 9 Notes. Momentum: inertia in motion ρ = m v ρ (rho) units of kgm/s VECTOR QUANTITY Inertia of...

Momentum Introduction

Momentum IntroductionCh 9 NotesMomentum Momentum: inertia in motion = m v (rho)units of kgm/sVECTOR QUANTITY

Inertia of an object depends on its mass AND velocityImpulse = Change in Momentumunits of NsBased on definitions of acceleration:a = F/m & a = v/t so F/m = v/t Cross multiply to get F t = m v

ImpulseImpulse = Change in Momentumunits of N*sImpulse (I) = FtA measure of how quickly momentum changes.Or how quickly a force acts upon an object.Impulse Examples

Large Force, Little TimeLittle Force, Larger Time

Conservation of MomentumFor closed systems, the sum of the momenta must be conserved between the objects in the system.initial = finalNonstick perfectly elasticm1v1i + m2v2i = m1v1f + m2v2f

Sticky inelasticm1v1i + m2v2i = (m1+m2) vf

Impulse Momentum TheormIf momentum must be conserved, then

The impulse of an object and its momentum must be conserved, so

= m v and I = Ft Therefore: mv = Ft for objects in the same system

Momentum ExampleWhat is the momentum of a 250kg car that is traveling at 9 m/s?

Impulse ExampleWhat is the impulse of a ball that collides with a wall in .03s with a force of 150N?Impulse Momentum TheormWhat is the change in momentum of an object that has collides with a wall with an impulse of .15 N*s?Agenda 5/5Review LOCOE Quizzes

Review Impulse and Momentum

Momentum Lab Collisions

Revenge of the Fifth

Agenda 5/6/15Warm-UpElectrostaticsConservation of Momentum LabExploding Carts!!

Change in Momentum: CollisionsCollisionsElastic CollisionsTwo objects collide and bounce off of one anotherEx: Tennis ball and racketMomentum is conserved m1v1i + m2v2i = m1v1f + m2v2f

CollisionsInelastic CollisionsTwo objects collide and stick togetherTwo masses become one mass moving at a slower velocitym1v1i + m2v2i = (m1+m2) vf

ExampleA 2kg bowling ball is rolled into a .5kg pin. The ball is moving with a velocity of 2.5m/s and collides elastically with the pin. After the collision the ball is moving at .25 m/s. How fast was the pin moving after the collision?Agenda 5/8/15Circuits Warm-UpNeed calculators

Momentum and Impulse Lab

Complete Collision Problems and turn in on calcs

Momentum/Impulse Quiz MondaySafetyWear gogglesNo one else should be near the table when you chopYou must chop THROUGH the boardIf you stop at the board you will hurt yourselfClose your fingers when you chopIf you dont you could hurt them