##### # Unit 7, Quiz #1 1. Suppose the time taken for light to bounce to and fro between the parallel mirrors of a light clock is 1 second, in the frame of reference of this light clock. As seen by another observer moving at a high speed at right angles to the to-and-fro motion of the bouncing light, the time taken would be a. also 1 second. b. less than 1 second. c. more than 1 second.   2. When a blinking light source moves towards you, its speed changes but its frequency remains constant. remains constant, but its frequency can change. stays the same, as does its frequency.   3. According to special relativity, one can travel at increased rates both forwards and backwards in time. backwards in time only. forwards in time only.   4. A woman standing on the ground sees a rocket ship move past her at 95% the speed of light. compared to when the rocket is at rest, the woman measures the rocket's length as a. longer. b. shorter. c. the same length.   5. When an object is pushed to relativistic speeds, its mass is a. greater than at rest. b. smaller than at rest. c. the same as at rest.   6. An astronaut traveling at .87c holds a 1-meter stick in her hand, moving forward in spear-like fashion. The astronaut sees the spear's length as a. 0.5 m b. 0.87 m c. 1 m d. 1.25 m e. 1.5 m   7. A spaceship that is traveling very fast with respect to your frame of reference, fires a light beam that travels at speed c with respect to the spaceship. You measure the light beam's speed to be a. less than c b. more than c c. equal to c   8. According to the special theory of relativity, if you measure your own pulse while traveling at very high speeds, you would notice your pulse rate to a. increase b. decrease c. be the same as usual   9. Ima Rushin is moving at 99.99% the speed of light relative to a stationary reference frame. Calculate the length of her 2-meter stick as viewed from the stationary reference frame. PSYW     10. Suppose in another world the speed of light were 10 m/s, the speed of a fast runner. Using complete sentences, describe some effects on Olympic Game events (sprints, long-distance runs, pole-vaulting, high jumping, etc.) in this world. Use the back of this sheet if necessary.     ### Useful Web Links Information on the topic of relativity can be found at The Physics Classroom. Additionally, animations and an interactive Shockwave movie can be found at the Multimedia Physics Studios and at the Shockwave Physics Studios.
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