Physics help!

[h2a2n]

I am almost done with my assignment, but I am stumped with one question. I need to determine the magnitude of the net gravitational force on the moon.

The gravitational force FSM that the sun exerts on the moon is perpendicular to the force FEM that the earth exerts on the moon. The masses are: mass of the sun = 1.99X10^30 kg, the mass of earth = 5.98X10^24 kg, mass of moon = 7.35X10^22 kg. The distances are Sun to moon = 1.50X10^11 m and earth to moon = 3.85X10^8 m.

I know how to calculate angular momentum, but I have no idea how to apply it to this problem.

So can someone point me in right direction so I can get started.

[lpxxfaintxx]

It sounds like a vector problem. You have one vector moon-sun plus another vector moon-Earth. Add the two. Since they're perpendicular, this means the sum is sqrt(a^2+b^2).

[h2a2n]

It is a vector problem,

Fgrav = (G*Msatellite*Mcenter)/r^2

G is 6.67 x 10-11

still stumped.

[lpxxfaintxx]

Calculate the F for moon-sun (Fsun) and the F for moon-Earth (Fearth).

Draw a vector from left to right Fsun, and at the end of it, draw a vector up Fearth (right then up is perpendicular). Draw another vector from start to finish (completing the right triangle). This vector is the net gravitational force.

The length of the hypotenuse of this right triangle can be found using Pythagoreum's Theorem, c^2=a^2+b^2 where a and b are the sides and c is the hypotenuse of the right triangle.

a is Fsun, b is Fearth, so solve for c.