Physics
posted by Anonymous .
Four 7.5 kg spheres are located at the corners of a square of side 0.74 m. Calculate the magnitude and direction of the gravitational force on one sphere due to the other three.

Use symettry. YOu know the force will be diagonal.
the side components will be
2G*m^2/.74^2 Cos45
and the diagonal will be
G*m^2/(.74*1.414)^2
add 
i got 1.71E8 and that was wrong and then i got 1.03E8 and it was still wrong

with sig figs the answer should be
2.0*10^8 N towards the center of the circle