1. READING QUIZ For an inelastic collision between two objects,
"the total kinetic energy of the objects changes.",
"the total momentum of the objects changes.",
"the total potential energy of the objects changes."

2. Magnitude = mass times speed = mv Direction = same as velocity
Momentum is a vector:
Magnitude = mass times speed = mv
Direction = same as velocity
(To be more precise, this is the linear momentum.)
Fig. 7.4

3. Momentum is important because it can be conserved,
just like mechanical energy.

4. We also want to know about changes in momentum. Notation:
We also want to know about changes in momentum. Notation: initial momentum pi = mvi
final momentum pf = mvf
change in momentum Dp = pf - pi

5. Change in momentum = Impulse.
We can rearrange F = ma to be:
Dp = FDt
Or,
Change in momentum = Impulse.
(Calculate force on baseball…)

6. If the net external force acting on a system of objects is zero, the total momentum of the system is conserved.

7. Fig. 7.12

8. What makes a rocket move?
Fig. 7.13
(Is mass of rocket constant? Is air needed?)

9. Fig. 7.14
Fig. 7.14

10. Lecture Quiz - Question 1: Which ball experiences a greater force?
Elastic
Perfectly inelastic.
Fig. 7.p136d

11. Fig. 7.15
Fig. 7.15

12. Fig. 7.17
Fig. 7.17

13. Fig. 7.18
Fig. 7.18

14. Try This Box 7.4
Fig. 7.p131a

15. Question 35
Fig. 7.p139a