Q.

The time period of a geostationary satellite is 24 h, at a height 6RE (RE is radius of earth) from surface of earth. The time period of another satellite whose height is 2.5 RE from surface will be,            [2019]
 

1 62 h  
2 122 h  
3 242.5 h  
4 122.5 h  

Ans.

(1)

Time period of Geostationary satellite is,

        T=2πa3GMT2a3

    T12T22=a13a23(24)2T22=(7RE)3(3.5RE)3

T22=(24)2×(3.5)3(7)3T2=(24)28=62 h.