1. Ch.7 Linear Momentum and Collisions

2. (Use a pompom instead of marshmallow.)

3. 7.1 Momentum Moving objects have momentum. Same momentum:
(2m) v = m (2 v )
Because momentum is the product of mass and velocity, an object's momentum changes whenever its mass or velocity changes.
Sometime p is referred to as linear momentum, as opposed to angular momentum ( of a rotating object).

4. Momentum is a vector quantity.
The momentum vector points in the same direction as the velocity vector.
Both objects have the same mass, 1 kg, and both hit the floor with the same speed, 4 m/s.
Since the ball bounces, its change in momentum is double.

5. https://youtu.be/3tH1btwdss4

6. The waterwheels used in gold mining operations during the California Gold Rush were not very effective.
Lester A. Pelton designed a curve-shaped paddle that caused the incoming water to make a U-turn upon impact. The water “bounced,” increasing the impulse exerted on the waterwheel.

7. Kinetic Energy
Momentum
Formula
Units
Scalar or vector?

8. Total momentum is a vector sum:
The momenta of objects headed in opposite directions can partially or totally cancel one another. Thus, it is possible for system of several moving object to have a total momentum that is positive, negative, or even zero.
Momentum of ducks:
Momentum of goose:
Total momentum of system:

9. p. 233
7.) it doubles
8.) its the same
9.) momentum doubles, KE quadruples
10.) No; momenta can cancel, but kinetic energy is a scalar quantity that cannot cancel.

10. 7.2 Impulse A force acting for a time produces an impulse.
An impulse changes an object's momentum.
Pelton
wheel:

11. Use the average force, Fav, and the time over which the force acts, t, to analyze problems.

12. If the change in momentum occurs over a longer time, the force of impact is smaller:
If the change in momentum occurs over a smaller time, the force of impact is larger:

13. Applications:

14. p.241 22.) change in momentum 23.) change in momentum
24.) because it doesn't increase the time of impact
25.) D<C=B<A
26. a) equal
b) greater