Answer:
about 0.365 m/s
Step-by-step explanation:
You want to know the velocity of an astronaut who starts from rest and fires a thruster that expels 35 g of gas at 875 m/s.
Momentum
The total momentum of the system is the same before and after the thruster is fired: 0.
If v is the velocity of the astronaut, it must satisfy the equation ...
(84)v +(0.035)(875) = 0
v = -(0.035)(875)/(84) ≈ -0.3646
The velocity of the astronaut is about 0.365 m/s in the direction opposite of the expelled gas.
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Additional comment
We have used (kg·m/s) as the units of momentum. 35 g = 0.035 kg. We have also assumed that the mass of the system before firing is a total of 84.035 kg