Question

Two observers agree to test time dilation. They use identical clocks, and one observer in frame S’ moves with speed v=0.8c relative (along +x-axis) to the other observer in frame S. When their origins coincide they start their clocks. They agree to send a signal when each of their clocks reads 90min and to send a confirmation signal when each receives the other’s signal. (a) At what time does the observer in S receive the first signal from the observer in S’? (b) When does the observer in time S receive the confirmation signal? (c) At what time (as measured in S’) does the observer in S’ receive the first signal from the observer in S? (d) When does the observer in S’ receive the confirmation signal from the observer in S?

Answer 1