Question

The moon has a mass of 7.35×10

22

 kg

7.35×1022 kg and a radius of 1.738×10

6

 m

1.738×106 m. At what speed must a rocket be launched from the surface of the moon so as not to fall back to the moon?

Answer 1

The first cosmic velocity will be

$$v=\sqrt{GM/R}=1680\text{ m/s}.$$