ID:________NAME:___________________________________________________DATE:_________________________________CLASS:__________________
Essential Questions: Based on what you learn in this chapter, you should be able to
provide a Physics explanation for these questions
 Why is “follow through” important in golf, baseball, and boxing?
 Why does it hurt less to fall on a wooden floor rather than a cement floor?
 We talk about “changing momentum.” Is it possible for a very massive object (such as a truck)
to have the same momentum as a not so massive object? (such as a skateboard)
 Why does bungee jumping use an elastic band rather than a regular rope?
 All other HW questions and questions in notes
All Objectives: You should be able to:
 Define Momentum (7.1)
 Define impulse and describe how it affects changes in momentum (7.2)
 Explain why an impulse is greater when an object bounces than when the same object comes to
a sudden stop (7.3)
 State the Law of Conservation of Momentum (7.4)
 Distinguish between an elastic collision and an inelastic collision (7.5)
Enduring Understandings: These are the key concepts you should know from this
chapter:
 The momentum of an object is the product of its mass and its velocity (p = mv)
 If the momentum of an object changes, either its mass, or velocity, or both change
 The change in momentum depends on the force that acts and the length of time it acts
 Impulse is average force multiplied by the time during which it acts (I = Ft)
 The impulse exerted on something is equal to the change in momentum it produces
 Ft = mvf - mvi = m(vf - vi)
 If the change in momentum occurs over a short period of time, the force of impact
is large.
 If the change in momentum occurs over a long period of time, the force of impact
is small.
 ***The same impulse can result from 2 different forces***
 The Law of Conservation of Momentum states that momentum is conserved when there is no
net external force
 When objects collide in the absence of external forces, momentum is conserved no
matter whether the collision is elastic or inelastic
Common Misconceptions:
Misconception/ False Statement
Correct Statement
Impulse = momentum
Momentum is conserved only when collisions are
perfectly elastic
Bouncing is good!
Impulse = CHANGE in momentum
Even in an inelastic collision, net momentum before the
collision is equal to net momentum after the collision.
Bouncing produces more impulse! It is more dangerous to
“bounce” than to “stop”
You will be given the following formulas in this
column; you must know HOW and WHEN to
apply them:
This column explains what the formulas
mean IN WORDS; you will NOT be given
this info on the test.
p = mv
Momentum = mass x velocity
I = Ft
Impulse = Force x time
Ft = m [vf – vi ]
Impulse = the CHANGE in momentum
(m1 vi1 ) + (m2 vi2 ) = (m1 vf1 ) + (m2 vf2 )
Elastic collision equation
(momentum before collision = momentum after
collision)
Inelastic collision equation
(momentum before collision = momentum after
collision)
(m1 vi1 ) + (m2 vi2 ) = (m1 + m2) vf
Make sure you review ALL:
 HW
 Notes
 Quizzes
 Assignments
 Etc.