A LASER BEAM AIMED AT THE MOON TAKES 2.56 SECONDS TO RETURN AFTER REFLECTION AT MOON'S SURFACE.FIND THE RADIUS OF LUNAR ORBIT AROUND EARTH.

Asked by Karishma Sayyad | 9th May, 2014, 04:16: AM

Expert Answer:

Let 'x' be the distance between the earth's surface and moon's surface.
Then the total distance travelled by the laser beam from earths surface to moon's surface and then after reflection back to earth will be '2x'
Given the time taken by the laser beam to return after reflection at moon's surface is 2.56 seconds.
 i e t = 2.56 sec
Laser beam being an electromagnetic wave, travels with the speed of light ,s = 3×108 m/s
 
Therefore the total distance travelled by the beam = speed of the beam × total time taken by the beam 
 
   2 x = 3×108 m/s × 2.56 seconds.
= 7.68 × 108 m
     x = 3.84 × 108 m.
 
Thus we can say that the radius of the lunar orbit around earth is  3.84 × 108 m

Answered by Jyothi Nair | 9th May, 2014, 09:13: AM