# Calculate the magnitude of the gravitational force

1. Oct 4, 2007

### mathcrzy

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

Four 9.0 kg spheres are located at the corners of a square of side 0.72 m. Calculate the magnitude of the gravitational force on one sphere due to the other three.

2. Relevant equations

Fg=G(M1)(M2)/r^2

3. The attempt at a solution

I figured out the force the each of the two spheres perpendicular to the corner one by doing Fg=[(6.67e-11)(9)(9)]/[.72^2]=1.04e-8. then i used the pathageon theorum to find the radius to the sphere in the opposite corner of the square by doing square root of .72^2+.72^2=1.02. I am now having trouble finding the force of the two corner balls pulling at a 45 degree angle towards the middle of the square.

2. Oct 5, 2007

### learningphysics

For the 3rd force at a distance of 1.02 m... apply the force formula to get the magnitude of the force... ie Gm1m2/(1.02)^2

then what is the x-component of this force... what is the y-component of this force...

add up the x-compoents of all 3 forces.

add up the y-components of all 3 force.

then you have the x-component and y-component of the net force... get the magnitude...