In the classic anime series Cowboy Bebop, Spike finds himself in a bad situation: floating in space without a spacesuit, and drifting away from the only nearby ship.

Fortunately, Spike remembers that the total momentum of a system of bodies will be conserved in the absence of external forces. He fires his pistol in order to change his velocity so that he will drift onto a large piece of debris; he can then jump from it back to safety.

Will this really work? Let's find out.

Spike and his (empty) gun have a mass of **M = 70 kg**.
Each bullet in his gun has a mass of **m = 0.05 kg**.
Spike and his gun and his bullet are all drifting to the
left, away from safety, at **v = 3 m/s**.

Spike fires the bullet so that it ends up travelling
at **v = 400 m/s** to the left.
What is the final velocity of Spike and the gun in his hand?

Copyright © Michael Richmond. This work is licensed under a Creative Commons License.