Answer:
0.4 m/s
Explanation:
Law of conservation of momentum tell us that the change in momentum of the hammer will be equal to the change in momentum of the astronaut
change in momentum of hammer = change in momentum of astronaut
2 kg (14 m/s - 0 m/s) = 70 kg * (v-0)
v = 0.4 m/s
The formula for accelerational displacement is at^2/2, so we know that 3.9t^2/2 = 200, or 3.9t^2 = 400. t =

, at = v, so