Answer: 2.47 seconds.
Explanation:
We know that at this point, the distance between the moon and Earth is:
D = 2.3*10^5 miles
We want to know how much time does need the light to go from Earth to the moon and then return to Earth.
Here we can use the relationship:
Time = Distance/Speed
Distance is equal to two times the distance between Earth and the moon (because the path is traveled two times), then:
Distance = 2*(2.3*10^5 miles) = 4.6*10^5 miles.
The speed is equal to the speed of light, we know that this is:
Speed = 186,282 mi/s
Then the time will be:
time = (4.6*10^5 mi)/( 186,282 mi/s) = 2..47 s
The light needs 2.47 seconds to go from Earth to the moon and come back.
