Physics 222 Worksheet: Chapter 26, Relativity

Here’s a web page that animates some of the concepts of relativity: http://www.theory.caltech.edu/people/patricia/st101.html

Questions 1 - 3 refer to this situation. A rocket leaves Earth and travels to a star that is 20 light years away as seen by the Earth. The speed of the rocket is 0.8c relative to the Earth.

1) The time for the trip as measured on Earth is

a) 25 years.

b) 20 years.

c) 16 years.

d) 12 years.

2) The time for the trip as measured on by the astronauts in the spaceship is

a) 25 years.

b) 16 years.

c) 15 years.

d) 12 years.

3) The distance from Earth to the star as measured by the astronauts is

a) 25 light years.

b) 20 light years.

c) 16 light years.

d) 12 light years.

4) Which of the following statements is not true according to the theory of relativity?

a) As an object increases speed its mass increases.

b) As an object increases speed its length increases.

c) As an object increases speed its kinetic energy increases.

d) As an object increases speed its momentum increases.

5) Compared to clocks in a stationary reference frame moving clocks run

a) faster.

b) slower.

c) at the same rate.

6) When you approach a light source, the light from that source has a speed

a) greater than c.

b) less than c.

c) equal to c.

7) There is an upper limit on velocity. Thus there is also an upper limit on

a) kinetic energy.

b) mass.

c) momentum.

d) all of the above.

e) none of the above.

8) We do not usually observe relativistic effects in our daily lives because

a) we are moving at speeds much less than c.

b) we are much larger than atoms.

c) we are much heavier than elementary particles.

d) we are much lighter than stars.

Ans: 1-a, 2-c, 3-d, 4-b, 5-b, 6-c, 7-e, 8-a