A rocket leaves earth at speed on its way to a planet a distance as measured by earth
PHYSICS · Multi-part · A Level · Physics · Turning points in physics · Turning points in physics
Problem
A rocket leaves earth at speed 0.80c on its way to a planet a distance 20ly as measured by earth. When the rocket gets to the planet it sends a light signal to earth.
(a) When does the signal get to earth according to (i) earth and (ii) rocket?
(b) Illustrate your answers with a spacetime diagram.
(c) At t=0, another rocket leaves the planet returning to earth with speed 0.80c relative to earth. As the rocket sets out it sends a light signal to earth. When does the light signal arrive at earth according to (i) earth and (ii) rocket clocks?
(d) Illustrate your answers on a spacetime diagram.