Question

An astronaut having mass 320 kg with equipment included is attempting an untethered space walk. The astronaut is initially at rest with respect to the nearby spacecraft, but discharges 30.0 g of nitrogen gas at 900.0 m/s from a portable propulsion unit. How fast is the astronaut moving after doing that?
84 m/s

27 m/s

0.36 m/s

0.084 m/s

Answer 1

This can be solved using momentum balance, since momentum is conserved, the momentum at point 1 is equal to the momentum of point 2. momentum = mass x velocity
m1v1 = m2v2
(0.03kg x 900 m/s ) = 320(v2)
v2 = 27 / 320
v2 = 0.084 m/s is the speed of the astronaut