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Need Conceptual Physics Help in preparation for test

  1. Feb 11, 2009 #1
    Please answer as many as possible! Thanks!

    1. If the kinetic energy of a particle is zero, what is its linear momentum?

    2. If the speed of a particle is doubled, by what factor is its momentum changed? By what factor is its kinetic energy changed?

    3. If two particles have equal kinetic energies, are their momenta necessarily equal? Explain.

    4. If two particles have equal momenta, are their kinetic energies necessarily equal? Explain.

    5. An isolated system is initially at rest. Is it possible for parts of the system to be in motion at some later time? If so, explain how this might occur

    6. In an isolated system, if two objects collide and one is initially at rest, is it possible for both to be at rest after the collision? Is it possible for one to be at rest after the collision? Explain.

    7. Explain how linear momentum is conserved when a ball bounces from a floor.

    8. Is it possible to have a collision in which all of the kinetic is lost? If so, cite an example.

    9. In a perfectly elastic collision between two particles, does kinetic energy of each particle change as a result of the collision?

    10. When a ball rolls down an incline, its linear momentum increases. Does this imply that momentum is not conserved? Explain.

    11. Consider a perfectly inelastic collision between a car and a large truck. Which vehicle loses more kinetic energy as a result of the collision?

    12. Can the center of mass of a body lie outside the body? If so give examples.

    13. A sharpshooter fires a rifle while standing with the butt of the gun against his shoulder. If the forward momentum of a bullet is the same as the backward momentum of the gun, why is it not as dangerous to be hit by the gun as by the bullet?

    14. Early in this century, Robert Goddard proposed sending a rocket to the Moon. Critics took the position that in a vacuum, such as exists between the Earth and the Moon, the gases emitted by the rocket would have nothing to push against to propel the rocket. According to Scientific American (January 1975), Goddard placed a gun in a vacuum and fired a blank cartridge from it. (A blank cartridge fires only the wadding and hot gases of the burning gun powder) What happened when the gun was fired?

    15. Does the center of mass of a rocket in free space accelerate? Explain. Can the speed of a rocket exceed the exhaust speed of the fuel? Explain.
     
  2. jcsd
  3. Feb 12, 2009 #2

    tiny-tim

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    Science Advisor
    Homework Helper

    he he he :rofl: :rofl:

    nooo … you start :wink:

    try 1 and 2 first. :smile:
     
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