Posted by cassie on .
newtons law of gravitation says that the magnitude F of the force exerted by a body of mass m on a bod of mass M is F=GmM/r^2 where G is the gravitational constant and r is the distance between the bodies.
a)find dF/dr and explain its meaning. What does te minue sign mean?
b)suppose it is known that the earth attracts an object with a force that decreases at a rate 2N/km when r=20,000km?

calculus 
bobpursley,
Do you proof your typing? You should. Part b) makes no sense
Part a) requires some thinking. What is a gradient? What happens when one is going in the negative direction?
I will be happy to critique your thinking on this.