The radius of the Earth is r. A satellite of mass 100 kg is at a point which is a distance 3r above the Earth's surface. What is the satellite's weight?
A) 6.3 N
B) 110 N
C) 61 N
D) 38 N

Question

Quizplus · Accepted Answer

Weight of the satellite = (mass of satellite) x (acceleration due to gravity at a height of 3r from Earth's surface)
Acceleration due to gravity at a distance of 3r from the surface of the Earth is given by:
g′=(mE)/(r+3r)2
g′=(mE)/(16r2)
where mE is the mass of the Earth.
Now, weight of the satellite = (100 kg) x g′
Weight of the satellite = (100 kg) x [(mE)/(16r2)]
Weight of the satellite = (100)(9.81)/16 = 61N

The Radius of the Earth Is R