A satellite weighs 400 newtons on the surface of earth. What is its weight at a distance of one earth radius above the surface of earth?

Answer 1

The force of gravity is GMm/r^2

Here, that quantity is equal to 400 newtons.

r = 1 Earth radius because Earth's surface is 1 radius away from its center.

Plugging in r = 1, makes GMm equal to 400 N.

To simulate being 1 earth radius above the surface of the earth, one would make the total distance to the earth's center of mass equal to 1 + 1 = 2 radii.

Plug r = 2 into the equation.

Now we get F = GMm / (2^2) = GMm/4.

Since GMm was equal to 400 N, divide 400 by 4 to get a new gravitational force of 100 N.