Question

A radar signal is reflected from the moon. It is detected after a 2.58 s time lapse between sending and

receiving. How far away in kilometers is the moon?

Answer 1

The distance to the moon is
`3.87*10^5km.`

Step-by-step explanation:

Here the distance to the moon is half the distance traveled by light (the radar signal) in 2.58 seconds.

Since the speed of light is
`c= 3*10^8m/s`, the distance
`d` traveled by light in 2.58s is

`d= ct = (3*10^8m/s)(2.58s) \\\\d = 7.74*10^8m.`

Half of this distance is

`(d)/(2) = 3.87*10^8m`

which in kilometers is

`\boxed{3.87*10^5km}`

and it is this distance to the moon.