Question

Light in a vacuum travels at a constant speed of 3x108 m/s. If the Moon's average distance from the Earth is 38324203 km, how long would it take for a beam of light to travel from the Earth, to the Moon, and back to the Earth again?

Answer 1

In this case we will use the next formula

`s=(d)/(t)`

where s is the speed, d is the distance and t is the time

In ur case

s= 3x10^8 m/s

we multiply by two the distance given because it is the double of the distance

d=2(38324203 )=76648406 km

and then we need to transform it into m

d=7.66x10^10m

Then we substitute

`3*10^8=(7.66*10^(10))/(t)`

Then we isolate the t

`t=(7.66\cdot10^(10))/(3\cdot10^8)=255.5s`

ANSWER

t=255.5 s