Speed of Impact of meteoroid

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!


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