A communcations satellite of mass 200kg is in circular orbit of radis 4x10^4 km measured from the center of the earth. What is the gravitational force on the satellite and what fraction is this of its weight on the surface of the earth?

1 answer

On the surface of the earth, the weight weight would be
W = M*g = 200*9.8 = 1960 Newtons

The Earth's radius is 6370 km. Your orbit radius is 40,000 km. The weight is proportional to 1/R^2, so at 40,000 km the weight is
1960*(6370/40,000)^2 = 49.7 Newtons