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Homework Statement
The Earth has a mass of 5.98 x 1024 kg and the moon has a mass of 7.35 x 1022 kg. The distance from the centre of the moon to the centre of the Earth is 3.84 x 108 m. A rocket with a total mass of 1200 kg is 3.0 x 108 m from the centre of the Earth and directly in between the Earth and the moon. Find the net gravitational force on the rocket from the Earth and the moon.
Homework Equations
Fnet = Gm1m2/r2
The Attempt at a Solution
m1 (earth)=5.98 x 1024 kg
m2 (moon)=7.35 x 1022 kg
m3 (rocket)=1200kg
m1 is 3.85 x 108m from the centre of m2
m3 is 3.0 x 108 m from the centre of m1
My problem is trying to figure out how far the rocket(m3) is from the moon(m2). The question says that the rocket is directly in between the Earth and the moon, so does that mean that the distance is 3.0 x 108 m to the centre of the moon and to the centre of the earth?
Next I would use Fnet = Gm1m3/r13 + Gm2m3/r23 and solve the question. In the example I read it said "add their magnitudes since both forces act in the same direction". In this question the forces would be acting in different directions, one toward the moon and the other toward earth. Does this mean I subtract the magnitudes instead of adding?