Answer:
The recoil speed of Astronaut A is 0.26 m/s.
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.
Answer:
2
Explanation:
BRAINLIEST?? AND THANK ME LATER!!! HOPE THIS HELPED!!!
The answer is B.
She can measure the mass of the water, marble and the graduated cylinder with the balance.
The volume of the water can be shown on the marked graduated cylinder, the volume of the marble can be measured by the volume difference of the water before and after the marble is put in.