The Moon's distance from Earth is measured very accurately by bouncing a laser beam off of a small mirror left on the surface of the Moon. If a laser is fired at the Moon and the signal returns in 2.6 seconds, what is the distance to the Moon
A)390,000 km
B)390,000 m
C)780,000 km
D)780,000 m

Question

Quizplus · Accepted Answer

The distance to the Moon is calculated by multiplying the speed of light (approximately 300,000 km/s) by the total travel time of the laser light (2.6 seconds) and then dividing by 2, since the light travels to the Moon and back. This calculation gives 390,000 km.

The Moon's Distance from Earth Is Measured Very Accurately by Bouncing