# Gravitational Force between two equal masses

1. Nov 14, 2011

### physgrl

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

Two equal masses are precisely 1 m apart from each other. The gravitational force each exerts on the other is exactly 2. What is the value of each mass?

*a. 1.73*10^5kg

b. 1.50*10^10kg

c. 2.50*10^5kg

d. 1.58*10^10kg

2. Relevant equations

F=Gmm/r^2

3. The attempt at a solution

I did
F=Gmm/r^2
2=G2m/1 (because the masses are equal)
m=2*1/2G
m=1/G
m=1.50*10^10kg

I dont know why B is wrong and A is right (according to the answer key);

2. Nov 14, 2011

### I like Serena

Hi physgrl!

I'm afraid that $m \cdot m \ne 2m$.

3. Nov 14, 2011

### physgrl

uups my mistake :s