Momentum:Momentum:Unit 5Unit 5

What is Momentum?What is Momentum? Momentum: ___________ in motionMomentum: ___________ in motion Momentum= Mass x VelocityMomentum= Mass x Velocity ____________ = Mass x Speed – when direction is ____________ = Mass x Speed – when direction is

not an important factornot an important factor Unit: kg x m/sUnit: kg x m/s The more __________ an object has, the more The more __________ an object has, the more

__________ there is possible.__________ there is possible. Speed affects the momentum of an object. Speed affects the momentum of an object.

EX. A fast car can have more momentum than a slow truck EX. A fast car can have more momentum than a slow truck w/ greater massw/ greater mass

Non-moving objects have no momentum at all.Non-moving objects have no momentum at all.

Impulse Changes MomentumImpulse Changes Momentum If ____________ changes, If ____________ changes,

then either mass or velocity then either mass or velocity or both has changed.or both has changed.

If mass is unchanged and If mass is unchanged and the ___________ changes the ___________ changes then acceleration results.then acceleration results.

Accelerations are produced Accelerations are produced by by Forces.Forces.

The greater the force= The greater the force= ______ an objects change ______ an objects change in velocity = Greater in velocity = Greater change in momentum.change in momentum.

ImpulseImpulse The quantity force X time The quantity force X time

interval = interval = ImpulseImpulse F(delta t) = ImpulseF(delta t) = Impulse The greater the impulse on an The greater the impulse on an

object, the greater the object, the greater the _____________ in momentum_____________ in momentum

Impulse = _____________ in Impulse = _____________ in MomentumMomentum

Impulse = Ft = delta (mv) Impulse = Ft = delta (mv) t is the time interval (delta t)t is the time interval (delta t) Unit = NsUnit = Ns

Increasing MomentumIncreasing Momentum Apply greatest force possible for as long as possible.Apply greatest force possible for as long as possible. EX. Baseball player and Golfer swinging as hard as possible EX. Baseball player and Golfer swinging as hard as possible

and following through with their swings.and following through with their swings. Forces involved in impulses usually vary from ________ Forces involved in impulses usually vary from ________

to instant.to instant. EX. The force is zero on a golf ball until it is struck by EX. The force is zero on a golf ball until it is struck by

the club; then the force increases rapidly as the ball’s the club; then the force increases rapidly as the ball’s shape becomes distorted. The force decreases as the shape becomes distorted. The force decreases as the ball returns to its original shape and increases in speedball returns to its original shape and increases in speed

__________________________________= Avg. force of impact measured in = Avg. force of impact measured in NewtonsNewtons

____________________________________ = Impact Force x time measured = Impact Force x time measured in Newton secondsin Newton seconds

Decreasing MomentumDecreasing Momentum The same impulse decreases your momentum The same impulse decreases your momentum

whether hitting a wall or haystackwhether hitting a wall or haystack The same impulse does ______ mean with the The same impulse does ______ mean with the

same force or time. same force or time. The product of the force and time are the same- The product of the force and time are the same-

not necessarily the force and time. not necessarily the force and time. Impact timeImpact time is ______________ when you hit the is ______________ when you hit the

haystack rather than the wall.haystack rather than the wall. Impact time = the time during which your Impact time = the time during which your

momentum is brought to _________.momentum is brought to _________. The ___________ the impact time = reduction in The ___________ the impact time = reduction in

force of impact = reduction in decelerationforce of impact = reduction in deceleration

ExamplesExamples EX of things that increase impact time and therefore EX of things that increase impact time and therefore

decrease impact forcedecrease impact force AirbagsAirbags Padded dashboard v. rigid dashboardPadded dashboard v. rigid dashboard Bending your knees when you jump from an elevated Bending your knees when you jump from an elevated

positionposition Relaxing your body when you fall to spread force of impact Relaxing your body when you fall to spread force of impact

over more musclesover more muscles Falling on a soft mat vs. hard floorFalling on a soft mat vs. hard floor Moving away from a punchMoving away from a punch

EX. Increasing the time of impact 100 times reduces EX. Increasing the time of impact 100 times reduces force of impact 100 times.force of impact 100 times.

Impact forceImpact force and and impact timeimpact time are ___________ are ___________ proportional.(Two variables that affect impulse)proportional.(Two variables that affect impulse)

Conservation of Conservation of MomentumMomentum

To accelerate an object, a ______ force must To accelerate an object, a ______ force must be applied to the object.be applied to the object.

To change the momentum of an object, you To change the momentum of an object, you must __________ an impulse on it.must __________ an impulse on it.

If no net force or net impulse acts on a system, If no net force or net impulse acts on a system, the __________ of that system cannot change.the __________ of that system cannot change.

The Law of Conservation of Momentum: In the The Law of Conservation of Momentum: In the absence of an external force, the momentum of absence of an external force, the momentum of a system remains unchanged.a system remains unchanged.

Elastic CollisionsElastic Collisions Elastic Collisions: When objects collide Elastic Collisions: When objects collide

___________ being permanently ___________ being permanently deformed and without generating heat.deformed and without generating heat.

Perfectly elastic collisions are not Perfectly elastic collisions are not common in the everyday world- some common in the everyday world- some __________ is produced in the collisions.__________ is produced in the collisions.

Inelastic CollisionsInelastic Collisions Inelastic Collisions: objects collide and Inelastic Collisions: objects collide and

become __________ or ___________ become __________ or ___________ together generating heat and becoming together generating heat and becoming ____________ in the process.____________ in the process.

Most collisions usually involve some Most collisions usually involve some ______________ force.______________ force.