Relativity Theory Practice Test

Review the following concepts if needed:

• Simultaneity Help
• Time in Relativity Help
• Time Dilation Help
• Spatial Distortion Help
• Mass Distortion Help
• General Relativity Help
• Curvature of Space Help
• Time Dilation by Gravitation Help
• Observational Confirmation of General Relativity Help 

Relativity Theory Practice Test

A good score is eight correct. Answers are given at the end.

1. A common unit of acceleration is the

(a) meter per second.

(b) kilometer per second.

(c) kilometer per hour.

(d) gravity.

2. Suppose that you have a spherical ball with mass of a hundred grams (100 g) at rest. If you throw the ball at three-quarters of the speed of light, what will its mass become, as measured from a stationary point of view?

(a) 100 g

(b) 133 g

(c) 151 g

(d) It cannot be calculated from this information.

3. Suppose that the ball in quiz question 2 has an apparent diameter, as measured laterally (sideways to the direction of its motion), of a hundred millimeters (100 mm) when it is speeding along at three-quarters of the speed of light. What will its diameter be when it comes to rest?

(a) 100 mm

(b) 133 mm

(c) 151 mm

(d) It cannot be calculated from this information.

4. If a space ship is slowing down, that is, losing speed in the forward direction, the perceived force inside the ship is directed

(a) toward the rear.

(b) toward the front.

(c) toward the side.

(d) nowhere; there is no acceleration force.

5. The Michelson-Morley experiment

(a) showed that the speed of light depends on the direction in which it is measured.

(b) showed that the speed of light depends on the velocity of the observer.

(c) showed that the speed of light does not depend on the direction in which it is measured.

(d) proved that the ether passes right through the Earth.

6. If you are in a spacecraft accelerating at 9.8 m/s ² through interplanetary space, you will feel the same force you would feel if you were sitting still on the surface of the Earth. This is an expression of

(a) a complete falsehood! Traveling through space is nothing at all like being on Earth.

(b) the fact that the speed of light is absolute, finite, and constant and is the fastest known speed.

(c) Einstein’s equivalence principle.

(d) the results of the Michelson-Morley experiment.

7. Suppose that you see a space ship whiz by at the speed of light. What is the time dilation factor k that you observe when you measure the speed of a clock inside that ship and compare it with the speed of a clock that is stationary relative to you?

(a) 1

(b) 0

(c) Infinity

(d) It is not defined

8. Some light beams will follow curved paths

(a) under no circumstances.

(b) when measured inside a space ship that is coasting at high speed.

(c) when measured in the presence of an extreme gravitational field.

(d) when measured from a reference frame that is not accelerating.

9. Suppose that you get on a space ship and travel toward the star Sirius at 150,000 km/s, which is approximately half the speed of light. If you measure the speed of the light arriving from Sirius, what figure will you obtain?

(a) 150,000 km/s

(b) 300,000 km/s

(c) 450,000 km/s

(d) It cannot be calculated from this information.

10. Clocks in different locations are impossible to synchronize from every possible reference frame because

(a) the speed of light is absolute, finite, and constant and is the fastest known speed.

(b) the speed of light depends on the location of the reference frame from which it is measured.

(c) the speed of light depends on velocity of the reference frame from which it is measured.

(d) there is no such thing as a perfect clock.

Answers

1. d

2. c

3. a

4. b

5. c

6. c

7. d

8. c

9. b

10. a