Special relativity Flashcards
In a stationary reference frame on Earth, a 2 m rod is moving at half the speed of light.By how much does its length contract? 27 cm 30 cm 25 cm It does not contract
27 cm
You measure your car to be 5 m long. How fast must you travel in your car for an outside observer to measure your car as being 4 m long? A. 0.4 c B. 0:6 c C. 0:75 c D. 0:8 c
0.6 c
You are on a platform at a train station, standing halfway between two clocks (A and B)that you observe to be synchronized. The clocks each emit a pulse of light when they strike 9:00am (in your reference frame). Since you are equidistant from the clocks, the pulses of light arrive at your location at the same time. At precisely 9:00am in your reference frame,a speeding train goes by at nearly the speed of light. The train travels in a direction parallel to the line joining the two clocks, and you observe that the train first passes in front of clock A, then in front of clock B (i.e. the train goes in the direction from A to B). Your physics professor, riding on the train, waves hello. What does your physics professor see?
Clock A emitted a pulse of light at the same time as clock B
Clock A emitted a pulse of light before clock B
Clock A emitted a pulse of light after clock B
Clock A emitted a pulse of light after clock B