First we review the force and potential energy of an object

First we review the force and potential energy of an object of mass m in a uniform gravitational field that points downward (in the k^ direction), like the gravitational field near the earth\'s surface. Find the force F (z) on an object of mass m in the uniform gravitational field when it is at height z=0. Express F (z) in terms of m, z, k^, and g.

Solution

As the gravitational field is uniform, the force being exerted on the body will be independent of its position along the z direction.

The force exerted on the body of mass m and with gravitational acceleration given as g, the force is given as

Fz = - mg k^

Also, the potential energy would be given as U = mgz

NOTE: For uniform gravitational field, the net gravitational force is determined solely by the product of gravitation acceleration that the field can produce and the mass of the body under consideration. However, for questions with varying field, the force being exerted would depend on the gravitational acceleration produced by the source at the position at hand.