Question

1. You and a friend are riding the subway, and sit at opposite ends of the car. You both count down from five, and then clap simultaneously, just as the train passes through a station. (It's an express train, so you don't slow down and stop at the station.)

   According to the predictions of special relativity, what would an observer on the subway platform observe as you passed through the station?

   		Your claps would not be simultaneous. One would occur before the other.
   		Your claps would occur at the same time.
   		Your claps would occur at the same time, but time would speed up for you, so they would occur more quickly.

2. Which of the following statements are true regarding light clocks and time dilation? (Select all that apply.)

   		If two observers are in relative motion, they will disagree about whose light clock is running more slowly.
   		Two light clocks are synchronized. They will remain synchronized even if one moves, because motion is relative.
   		A moving light clock ticks more quickly than a stationary one.
   		Because light clocks are just a way to measure time, and any clock could be synchronized with a light clock, the light clock thought experiment actually tells us that time itself slows down for moving objects.
   		A moving light clock ticks more slowly than a stationary one.

3. If I am stationary, and I see you move (from my point of view) at a speed of 25% of the speed of light, which of the following statements is true regarding how I will observe time passing for you?

   		I will observe time moving more slowly for you than for me.
   		I will observe time moving more quickly for you than for me.
   		Time will pass more slowly for you and for me, but I will not notice it because I am stationary.
   		I will measure no difference between the rate at which time passes for you and the rate that it passes for me.

Answer 1

Solution:

Question 1:According to the predictions of special relativity, what would an observer on the subway platform observe as you passed through the station?

Answer: Your claps would occur at the same time, but time would speed up for you, so they would occur more quickly.

Question 2:Which of the following statements are true regarding light clocks and time dilation? (Select all that apply.)

Answer:

Option (b)Two light clocks are synchronized. They will remain synchronized even if one moves, because motion is relative.

Option(d) Because light clocks are just a way to measure time, and any clock could be synchronized with a light clock, the light clock thought experiment actually tells us that time itself slows down for moving objects.

Question 3: If I am stationary, and I see you move (from my point of view) at a speed of 25% of the speed of light, which of the following statements is true regarding how I will observe time passing for you?

Answer: Time will pass more slowly for you and for me, but I will not notice it because I am stationary.

I will measure no difference between the rate at which time passes for you and the rate that it passes for me