ReactionForces Between ObjectsForce Both WaysLaw of ReactionForce PairsForce is Not AccelerationNot VelocityReactionReactionForces Between ObjectsForces Between ObjectsTry to kick a log.Try to kick a log.•The log may move (a force on the log from your foot)The log may move (a force on the log from your foot)•Your toe may break (a force on your foot from the log)Your toe may break (a force on your foot from the log)There are forces on each object at contact. There are forces on each object at contact.Force Both WaysForce Both WayssbFA falling ball on a paper A falling ball on a paper surface can break through.surface can break through.The ball exerts a force on the The ball exerts a force on the paper.paper.A falling ball on a hard A falling ball on a hard surface rebounds.surface rebounds.This is a change in velocity, This is a change in velocity, so the surface exerts a force so the surface exerts a force on the ball. on the ball. force of the ball on the surfaceforce of the surface on the ballbsFLaw of ReactionLaw of Reaction3For every action there is an equal and opposite For every action there is an equal and opposite reaction. reaction. Forces between two objects act in pairs.Forces between two objects act in pairs.FF1212 = = FF2121 (Newton’s third law) (Newton’s third law) rocketreaction force acts on the rocketacceleration increases or changes velocityhot gas is forced outForce PairsForce PairsForces between objects come in pairs.Forces between objects come in pairs.•A force from object 1 to object 2A force from object 1 to object 2•A force from object 2 to object 1A force from object 2 to object 1These are forces exactly equal and opposite.These are forces exactly equal and opposite.Force is Not AccelerationForce is Not AccelerationsbFThe ball breaking paper The ball breaking paper doesn’t stop.doesn’t stop.There is a small force on the There is a small force on the ball that slows it down.ball that slows it down.The acceleration is small The acceleration is small compared to the breaking compared to the breaking paper.paper.force of the ball on the surfaceforce of the surface on the ballbsFNot VelocityNot VelocitysbFOn a rebound the ground On a rebound the ground doesn’t move.doesn’t move.There is a small acceleration There is a small acceleration of the earth.of the earth.Mass of the Earth: 6 x 10Mass of the Earth: 6 x 102424 kg kgMass of the ball: 0.06 kgMass of the ball: 0.06 kgEarth’s acceleration is about Earth’s acceleration is about 1010-26-26 times smaller times smallerforce of the ball on the surfaceforce of the surface on the
View Full Document
Unlocking...