Question

A satellite is seen after every 8 hours. If it rotates opposite to that of the earth, what is its angular velocity about the centre of the earth? Assume the earth is perfectly spherical and the satellite is in the equatorial plane.

(a) pi/2

(b) pi/4

(c) pi/6

(d) pi/8

Answer 1

Right answer is (c) pi/6

The best I can explain: Angular velocity of the satellite if the earth were stationary; w’ = (2 x pi) / 8

 = pi / 4

Angular velocity of earth; w’’ = (2 x pi) / 24

 = pi / 12

Therefore, the angular velocity about the centre (w) = w’ – w’’

 = pi/4 – pi/12

 = pi/6