What is the maximum gravitational force between two uniform spheres?

[gmunoz18]

Homework Statement

A bowling ball (mass = 7.2 kg, radius = 0.10 m) and a billiard ball (mass = 0.48 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?
N

Homework Equations

F=G((m1*m2)/r^2)

g being gravitaional constant

The Attempt at a Solution

G((7.2*.48)/(.128))=1.801e-9

 

[Snazzy]

Where is r^2?

 

[gmunoz18]

i have solved it by


((7.2*.48)/(.128*2))*G

the only thing i didnt understand was where the objects relative to each other so i presumed they were touching.

 

[fluidistic]

Take a look at the formula F=\frac{Gm_1m_2}{r^2}. G is a constant and so are m_1 and m_2. Now we ask ourselves a question : " when will F reach a maximum when r varies?". It's obvious that more r is little more F is greater. So F reaches a maximum when r reaches its minimum. And what is the minimum of r? It's simply the sum of the radius of the 2 balls, as you did. So it will be 0.128\text{ m}.
Take care about what you wrote in the denominator of

((7.2*.48)/(.128*2))*G

, I think you forgot that r was squared and not multiplied by 2. Otherwise everything's good.