**1. The problem statement, all variables and given/known data**

Q: "Two meteoroids are heading for earth. Their speeds as they cross the moons orbit are 1km/s.

The first meteoroid is heading straight for earth, what is it’s speed of impact?"

Velocity = 1km/s

Rearth = 6.37E6 m

Dmoon = 3.84E8 m

G = 6.673E-11 N*m^2/kg^2

**2. Relevant equations**

E = 1/2mv[itex]^{2}[/itex] – √G*Mearth*m/r

**3. The attempt at a solution**

PE = (G * Mearth * m)/Dmoon

KE = -PE

1/2mv[itex]^{2}[/itex] = -PE

From there can cancel the masses (lower-case m) of the meteoroid and solve for v. I don’t feel like that is the right track. Shouldn’t it be as the PE goes to 0? Any help would be appreciated. Thanks!

http://ift.tt/1iWeyag