Two satellites A and B orbit the Earth in the same plane. Their masses are 7 m and 8 m, respectively, and their radii 5 r and 8 r, respectively. 8 r 5 r B 8 m A 7 m What is the ratio of their orbital speeds? 1. vB vA = r 8 5 2. vB vA = r 5 7 3. vB vA = r 8 7 4. None of these 5. vB vA = r 7

Explanation:

Given  

Satellite A has a mass of 7 m and at a radius of 5 r

Satellite B has a mass of 8 m and at a radius of 8 r

Orbital velocity is the velocity required by a satellite to remain in its orbit

Orbital velocity can be find by equating centripetal force on satellite and Force of gravitation between satellite and Planet

where M=mass of Planet

m=mass of body

r=distance from center of Planet

We can say that orbital velocity is independent of mass of satellite

For satellite A

For satellite B

divide 1 and 2 we get