Gravitational forces and multiple bodies problem

[jonathng]

Homework Statement

Four 335 kg spherical masses are placed on the corners of a square at coordinates (0, 0), (0, 1.50), (1.50, 0) and (1.50, 1.50) where all coordinates are in meters. What is the net gravitational force on the mass at (0, 0) due to the other three masses? Express your answer in polar notation with the angle in degrees.

Homework Equations

Fg=GMm/r^2
A^2+B^2=C^2

The Attempt at a Solution

I worked to find the distance from (0,0) to (1.5,1.5) and it was 2.1213 (using trig), I got that the angle is 45 degrees. But for some reason I am having trouble adding up the vectors to get the correct net force. I understand that we learned the tail-tip concept. The answer space is also only giving me one blank to fill in for the net force, this doesn't make sense to me, because if i am supposed to put the answer in polar notation i should give the vector an x and a y component, right? Any help with this will be greatly appreciated. Thanks!

 

[Doc Al]

With polar notation you specify a magnitude and an angle.

 

[jonathng]

Oh yea, you are right! Thanks a bunch! I need to sleep more.