Math Problem

Question

At a given point in its orbit, the moon is 2.4*10^5 miles away from Earth. How long does it take a light from a source on Earth to reach a reflector on the moon and then return to Earth? (Speed of light is 3.0*10^8 m/s)

Answer 1

There and back is a distance of 2 x 2.4 x 10^5 = 4.8 x10⁵ meters divided by the speed of light, 3.0 x 10⁸ meters = 1.6 x 10^-3 seconds