# Gravitational potential energy of the moon

1. Apr 23, 2005

### UrbanXrisis

How much work is done by the moon's gravitational field as a 1000kg meteor comes from outer space and impacts the moon's surface?

all I have to do is:
$$U=-\frac{Gm_1m_2}{r}$$
where $$_{m_1}$$ is the mass of the moon, $$_{m_2}$$ is the mass of the meteor, and $$_{r}$$ is the radius of the moon. is that correct?

2. Apr 23, 2005

### whozum

Well you want to integrate the gravitational force from infinity to the earths surface, because what 'r' ar eyou going to be using there?

3. Apr 23, 2005

### vincentchan

well, after the integration, you will get his equation:
$$U=-\frac{Gm_1m_2}{r}$$
whereas the r is the redius of the moon as UrbanXrisis suggest...

4. Apr 23, 2005

### whozum

Oh, I didnt see he specified r.