# sol13 - This means that it has some momentum in the upward...

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PHYSICS 103 Chapter 6 -- HW #13 Questions 2. Lee is correct because the momentum does not change—that is, the momentum is 12 kg m/s before and after the collision. The momentum can have any value as long as it does not change; it does not have to be zero. 6. In both cases—hitting the dashboard with or without padding— the change in momentum of a head is the same. Therefore, the impulses are also the same. But with the padded dashboard, the impact of the head with the dashboard takes a longer time and the forces that produce the impulse are therefore smaller. 14. Momentum is a vector. Both balls have the same initial momentum just before striking the floor. The momentum of the ball that does not bounce is zero afterward. Therefore its change in momentum is just the momentum it had before it hit the floor. The change in momentum of the ball that bounces is greater because it bounces.
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Unformatted text preview: This means that it has some momentum in the upward direction after it hits the floor. The change in momentum is just the vector difference in these two momenta. Because the vectors are in opposite directions, the size of the momentum change is the sum of the two sizes and therefore bigger than for the ball that did not bounce. Therefore the impulse on the ball that bounces is also greater. Exercise 8. The impulse acting on the ball is equal to the change in momentum experienced by the ball. ( 29 ( 29 ( 29 0.5 kg 6 m s 3 N s F t mv ∆ = ∆ =-= -× This impulse acts in the upward direction as indicated by the minus sign. (I chose the downward direction to be positive.) If the ball had bounced, it would have experienced a greater change in momentum (as explained in Question 14), which requires a greater impulse....
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