A communications satellite with a mass of 400 is in a circular orbit about the Earth. The radius of the orbit is 3.7×104 as measured from the center of the Earth.

Question

Calculate the gravitational force exerted on the satellite by the Earth when it is in orbit.

Answer 1

The Law of Universal Gravitation states that each particle of matter attracts every other particle of matter with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. Expressed mathematically,
F = GM(m)/r^2
where F is the force with which either of the particles attracts the other, M and m are the masses of two particles separated by a distance r, and G is the Universal Gravitational Constant. The product of G and, lets say, the mass of the earth, M, is sometimes referred to as GM or µ (the greek letter pronounced meuw as opposed to meow), the earth's gravitational constant.