Question

An 80 kg astronaut is floating at rest a distance of 10 m from spaceship when he runs out of oxygen to power him back to the spaceship.He removes his oxygen tank(3 kg) and push it into space away from the ship with a speed of 15 meter per second.

a.At what speed does he recoil toward the spaceship?
b.How long must he hold his breath before reaching the ship?

Answer 1

According to the momentum conservation law

MV = mv

V = mv/M = 3*15/80 = 0.563 m/s;

t = S/v = 10 / 0.563 = 17.78 s.