Created for CVCA Physics By Dick Heckathorn 18 November 2K + 4 Chapter 7 Created for CVCA Physics By Dick Heckathorn 18 November 2K + 4

Table of Contents 3 Car into Car vs Car into Wall 6 VW and Cadillac 7 Jacko catching a ball 8 Jacko getting off ice 9 CD 7.1 page 29 18 CD 7.1 page 30

Consider the consequences of driving a car into a head on collision with an identical car traveling toward you at the same speed – as opposed to colliding at the same speed against a massive concrete wall.

Which of these two situations would result in the greatest impact force? a. Colliding with the approaching car b. Colliding with the massive stationary wall c. Both would have the same impact

If a Cadillac and a Volkswagen have a head-on collision, which car will experience the greatest force? a. The Cadillac b. The Volkswagen c. Both the same

Jocko, who has a mass of 60 kg and stands at rest on the ice, catches a 20 kg ball that is thrown to him at 10 km/hr. How fast does Jocko and the ball move across the ice?

A fully dressed person is at rest in the middle of a pond on perfectly smooth ice and must get to shore. How can this be accomplished?

Concept Development page-29 1. A moving car has momentum. If it moves twice as fast, its momentum is twice as much.

2. Two cars, one twice as heavy as the other, moves down a hill at the same speed. Compared to the lighter car, the momentum of the heavier car is twice as much.

3. The recoil momentum of a gun that kicks is more than less than the same as the momentum of the bullet it fires.

4. If a man firmly holds a gun when fired, then the momentum of the bullet is equal to the recoil momentum of the gun alone gun-man system man alone

5. The momentum of an unlucky bug is suddenly changed as it splatters onto the windshield a. Compared to the force that acts on the bug, how much force acts on the bus? more the same less

5. The time of impact is the same for both the bug and the bus. b. Compared to the impulse on the bug, this means the magnitude of the impulse on the bus is more the same less

5. Although the momentum of the bus is very large compared to the momentum of the bug, c. the change in momentum of the bus, compared to the change of momentum of the bug is more the same less

d. Which undergoes the greater acceleration? bus both the same bug

abug mbus e. Which, therefore, suffers the greater damage? bus both the same bug Why? Fbus on bug = Fbug on bus mbug abug = mbus abus abug mbus mbug = abus

Concept Development page-30 Before Collision Granny’s mass 80 kg Ambrose’s mass 3 m/s Granny’s momentum 240 kg-m/s Ambrose’s mass 40 kg Ambrose’s momentum 0 kg Total momentum 240 kg-m/s

After Collision Granny’s speed Decreases Ambrose’ speed Increases Total momentum 240 kg-m/s Total mass of both 120 kg Speed 2 m/s