Work done by the moon?

Question

How much work is done by the Moon's gravitational field as a 940 kg meteor comes in from outer space and impacts on the Moon's surface?

Answer 1

Work = Force × Distance.

The "force" in this case is the force due the moon's gravity, and the "distance" is the distance that the meteor moves. (More accurately, it's the radial component of the distance that the meteor moves; that is the change ΔR in the distrance between the moon's center and the meteor).

But the force _changes_ as a function of distance; so in that case you have to use a definition that involves an integral:

Work = Integral(Force·dr)

You know that Force = GMm/r². Take it from there, and do the calculus.

Answer 2

None. The Moon is a lazy orb.