Calculating Energy Between Objects

[ryty]

Homework Statement

Two 0.54-k basketballs, each with a radius of 16 cm, are just touching.
A. How much energy is required to change the separation between the centers of the basketballs to 1.0 m?
B. How much energy is required to change the separation between the centers of the basketballs to 14 m?

Homework Equations

Im not sure what to use, but its probably obvious

The Attempt at a Solution

None, i don't know where to start

 

[srmeier]

this smells like a universal gravitational potential problem (assuming these balls are not on the surface of the earth), so what is your potential equation?

 

[ryty]

okay, F=G(m1)(m2)/r^2 but if the raduis of the balls are .16 m, do i use that as the radius, or do i double it beause the balls are the same size?

 

[srmeier]

(ignoring the detail with the radius) your expression solves for the force one ball exerts on another. Once you solve for this force, what good is it?

 

[ryty]

im kind of confused, am i using the right equation?

 

[srmeier]

no, use this equation.

$$U=G\frac{m_1m_2}{D}$$

where:
U= potential energy
G= Newton's gravity constant
D= distance from either respective centers

 

[ryty]

so it should look like this F=(6.67E-11)(.54)(.54)/.16 ?