Question

Duck Dodgers hops in his spaceship and leaves the Earth at a constant velocity of 0.6c in an attempt to reach the newly discovered Planet X before aliens from Mars.

a) Mission control on Earth sends an encoded message (a flashing beacon) to Duck Dodgers warning him about the progress of the Martian ship. The light pulses travel at a speed c relative to observers on the Earth. How fast are the pulses traveling relative to Duck Dodgers?

b) Duck Dodgers doesn’t understand the message that he received, so he sends a radio wave message back toward the Earth asking for clarification. The radio signal is traveling at a speed c relative to the Duck. How fast is the signal traveling relative to observers on the Earth?

c) The radio message is intercepted by Marvin the Martian who is behind Duck Dodgers but traveling in the same direction at a speed 0.8c relative to the Earth. How fast is the radio message relative to Marvin?

d) At this point, you might be asking yourself “What was the point of this problem?” What was the point of this problem?

Answer 1