# Gravitational force

Tags:
1. Oct 25, 2015

### kolua

1. The problem statement, all variables and given/known data
Two basketballs, each of mass 0.58 kg and radius0.12 m, are placed on a floor so that they touch each other. Two golf balls, each of mass 0.045 kg and radius 22 mm, are placed on a table so that they touch each other.
What is the ratio of the gravitational force exerted by one basketball on the other to that exerted by one golf ball on the other?
2. Relevant equations
F=GMm/r^2

3. The attempt at a solution
Fbb=G mbxmb/r12
Fgg=G mgxmg/r22

I got the result of 5.58
is this correct?

2. Oct 25, 2015

### PeroK

That's a weird question. It's also a poor question, as you can get the right answer by taking $r_b = 0.12m$ and $r_g = 0.022m$. Is that what you did?

3. Oct 25, 2015

### kolua

Yes and I got the ratio of 2757 not 5 sorry. is that correct?

4. Oct 25, 2015

### PeroK

Have a think about what $r$ should be when you have two objects of a given radius.

5. Oct 25, 2015

### kolua

Got it! I put the wrong number in calculator. THX!