Meteors will strike earth at what speed?

[gills]

Homework Statement

2 meteoroids are 160,000 km from Earth's center and heading straight toward Earth. One is moving at 10 km/s, the other at 20 km/s. At what speeds will they strike Earth?

Homework Equations

K + U = K_i + U_i

U = -GMm/R

The Attempt at a Solution

Ok, either I'm having a serious brain fart. But are those the right equations I'm concentrating on?

 

[G01]

Yes they are. You are on the right track if you know that those equation will help you with the problem.

 

[uber]

As well, remember that the change in potential energy is equal to the change in kinetic energy. What potential energy to the meteoroids have initially, and what will they have when they strike the surface of the earth?