Reading � Conservation of Momentum

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```					Reading “ Conservation of Momentum                                        Name: __________________

1.   Why are conservation laws “beautiful”?

2.   Why is there reason to believe that further conservation laws, beyond conservation of mass and

energy, are needed to completely describe nature?

3.   What is the assumption in the shopping cart example? (The “if”…) ___________________ , what

is the conclusion in the example? (the “you could not…”.)?

4.   What 3 characteristics of the shopping cart example indicated that there may be a new

conservation law involved? ______________________, ______________________,

___________________________

5.   If a gun has 25 times more mass than the bullet it will recoil at a velocity that is:

___________________________________

6.   Why do we bother to define the quantity of momentum?

7.   Define a closed system for momentum conservation.

8.   A cannon of mass 2000 kg fires an 8 kg shell at a velocity of 200 m/s. At what speed does the

cannon recoil?

9.   In the ion drive example what must the momentum after all exhaust gas has expelled be?

________ Why?

10. How can conservation of momentum be generalized to include massless light?

11. Why aren’t Newton’s laws still at the center stage of physics?

12. What argument does the author give for stating that conservation of momentum is not a

consequence of Newton’s laws?

13. Copy the differenced between KER and Momentum (table) on another sheet of paper and place

the paper in the “notes” section of your notebook. Check here after you have done so : ____

14. A spinning top has zero total _____________, but non-zero total _____________________.

15. Why can’t the moon suddenly fly off one way and the earth the other?, it would violate …

16. When do physicists employ the term “collision?

_________________________________________, give an example of an unconventional

collision..
17. For the example problem, if the velocity after the crash was 13 miles/hour how fast was Mr.

Nelson going before the crash? (All other values the same as in the example).

18. Why is it good that cars crumple during a collision?

19. What is the relationship between KE b and KE a for a “superball type” collision?

____________________ This type of collision is like the ________________ part of our lab.

20. What can’t the pool player (example pg 69) avoid doing no matter how hard they try?

21. The rate of transfer of momentum is equal to …

22. The relationship between F and momentum is analogous to what?

___________________________________________________________________. Force = rate

of ____________________________________________________.

23. If the amount of time it takes you to change your velocity by a fixed amount decreases, what

happens to the Force? (See example: walking into a lamppost)

24. From the example: ion drive, if ions are ejected at 50,000 m/s what is the change in time?

25. The equation p/t is derived under what assumption?

26. Force would be the _________ of a _______________ graph.

27. What is the simplest way to find change in momentum from a graph?

28. If viy= 1.5 x 104 km/hr, what is the magnitude of the 3rd piece’s velocity? From example:

explosion.

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