Question

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

Answer 1

Total time= 2.56 s

Step-by-step explanation:

Given that

`Distance = 2.4* 10^5\ miles`

So distance = 386242560 m

Velocity of light

`C= 3* 10^8\ m/s`

We know that

Distance = velocity x time

Now by putting then values

`time=(386242560)/(3* 10^8)`

t=1.28 s

So the total time = 2 x 1.28

total time= 2.56 s

Answer 2

Step-by-step explanation:

Given that,

Distance between moon and earth,
`d=2.4* 10^5\ miles`

1 mile = 1609.34 meters

`d=386241600\ m`

Speed of light,
`c=3* 10^8\ m/s`

We need to find the time taken by the light from a source on earth to reach a reflector on the moon and then return to earth. Time is given by :

`t=(d)/(c)`

`t=(386241600\ m)/(3* 10^8\ m/s)`

t = 1.28 seconds

Hence, this is the required solution.