# Homework Help: Gravitational force-help STUMPED

1. Jun 18, 2007

1. The problem statement, all variables and given/known data

A bowling ball (mass = 7.2 kg, radius = 0.10 m) and a billiard ball (mass = 0.41 kg, radius = 0.028 m) may each be treated as uniform spheres. What is the magnitude of the maximum gravitational force that each can exert on the other?

2. Relevant equations

F=G(m1xm2)/r^2

3. The attempt at a solution

i used the equation

F=[ 6.67x10^-11 ] [7.2] [.41]/1.2^2

but i keep getting a wrong answer of 1.2 x 10^-8 i dont know what i did wrong.....

2. Jun 18, 2007

I'm so confused, can anyone help me? :/

3. Jun 18, 2007

### Staff: Mentor

What's the distance between their centers?

4. Jun 18, 2007

i think it's assuming that they're touching so it would be the sum of the radiuses..

5. Jun 18, 2007

### Staff: Mentor

Right. And what would that sum be?

6. Jun 18, 2007

haha, oops so it's 0.128.... i thought i did that, mustve typed it wrong...but still, taht wouldnt make my way right would it?

7. Jun 18, 2007

### Staff: Mentor

Looks like you did use the correct value for the distance between the centers. I see nothing wrong with your solution.

8. Jun 18, 2007