Magnitude of the maximum gravitational force

[onyxorca]

Homework Statement

A bowling ball (mass = 5.9 kg, radius = 0.11 m) and a billiard ball (mass = 0.36 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?

Homework Equations

F=-Gm1m2/r^2

The Attempt at a Solution

6.67*10^-11*5.9*.36/-(.11+.028)^2 = -7.43913043 × 10^-9 N

right?

 

[willem2]

Right. altough I don't think the minus sign is right.

 

[onyxorca]

but that's the minus sign from the formula isn't it?

 

[willem2]

but that's the minus sign from the formula isn't it?

The formula is usually given without a minus sign. The question also asks for the magnitude of the force, which has to be positive.