Relativity Questions

1. Chris Parkes Relativity Questions

2. Motion

3. Q37.1 As a high-speed spaceship flies past you at half the speed of light, it fires a strobe light. An observer on board the spaceship measures a spherical wave front that spreads away from the strobe light with the same speed c in all directions. The wave front that you measure 1. is spherical and remains centered on the spaceship as it moves 2. is spherical and is centered on the point where the spaceship was when the strobe was fired 3. is not spherical but remains centered on the spaceship as it moves 4. is not spherical but is centered on the point where the spaceship was when the strobe was fired

4. Q37.5 Santiago stands on the ground as Miriam flies directly toward him in her spaceship at 0.5c. She fires a small rocket directly toward Santiago that flies at a speed of 0.8c relative to her spaceship. According to Santiago, the speed of the rocket is 1. 1.3c 2. faster than c but slower than 1.3c 3. c 4. faster than 0.8c but slower than c 5. 0.8c

5. Q37.2 simultaneity A high-speed train is traveling from Glasgow to Edinburgh. According to an observer at rest on the ground, the clocks at the railroad stations in Glasgow and Edinburgh both strike noon at the same time. According to a passenger on the train, when the Glasgow clock strikes noon, what time is it in Edinburgh? 1. noon 2. before noon 3. after noon 4. answer depends on the speed of the train

6. Glasgow Edinburgh Moving towards Edinburgh noon clock Moving away from Glasgow noon clock

7. Time dilation & length Contraction: Lorentz transforms Q37.4 Samir (who is standing on the ground) starts his stopwatch at the instant that Maria flies past him in her spaceship. At the instant that Samir’s stopwatch reads 8.0 s, Maria’s stopwatch reads 10.0 s. According to Maria, her spaceship is 100 m long (along the direction of motion). According to Samir, the length of her spaceship is 1. 64 m 2. 80 m 3. 100 m 4. 125 m 5. none of the above

8. Lorentz transforms Q37.3 Samir (who is standing on the ground) starts his stopwatch at the instant that Maria flies past him in her spaceship. According to Maria, at the instant that Samir’s stopwatch reads 16.0 s, Maria’s stopwatch reads 20.0 s. According to Samir, at the instant that Maria’s stopwatch reads 20.0 s, Samir’s stopwatch reads 1. 16.0 s 2. 20.0 s 3. 25.0 s 4. none of the above

9. Q37.6 According to the relativistic expression for momentum, if the speed of an object is doubled, the magnitude of the momentum 1. increases by a factor greater than 2 2. increases by a factor of 2 3. increases by a factor greater than 1 but less than 2 4. answer depends on the value of the initial speed