Answer:
The recoil speed of Astronaut A is 0.26 m/s.
Step-by-step explanation:
Given that,
Mass of astronaut A,

Mass of astronaut B,

Astronaut A pushes B away, with B attaining a final speed of 0.4,

We need to find the recoil speed of astronaut A. The momentum remains conserved here. Using the law of conservation of linear momentum as :

So, the recoil speed of Astronaut A is 0.26 m/s.