Question

An astronaut with a mass of `85 kg` is floating in space. If the astronaut throws a `15 kg` object at a speed of `2/5 m/s`, how much will his speed change by?

Answer 1

`-0.070 m/s`

Explanation:

Considering no other forces acting on the system,we can say momentum will be conserved.
So,after throwing the mass if velocity of the astronaut be `x m/s` then we can say,

`0 = 15*(2/5) + 85*x`
i.e `-0.070 m/s`
negative sign means that the astronaut will move opposite to the direction in which he threw the mass.