College Physics III, Chapter 39

                  Dr. Jianshi Wu, Ph.D.

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  1. Choose one from the following, which is not one of the two fundamental postulates in special theory of relativity:

  2. a) The laws of physics are identical in all inertial frames.
    b) The length of an object is contracted in the direction of its motion.
    c) Light travels in a vacuum with a speed c in any direction in all inertial frames.

  3. The life time of a muon at rest is 2.2 • 10-6 s. The life time of the muons in a beam with a speed 0.99 c is dilated by a gamma factor. The gamma factor is

  4. a) 0.99 .
    b) 0.141 .
    c) 7.09 .

  5. The two space ships are observed moving in opposite directions and with the same speed of 0.5 c. The speed of one space ship relative to the other is:

  6. a) 0.5 c .
    b) 0.8 c .
    c) 1.0 c .

  7. The rest energy of 1.0 kg of matter is

  8. a) 1.0 J .
    b) 3.0 • 108 J .
    c) 9.0 • 1016 J .

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