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.
I’m not entirely certain, but usually, spring symbolizes rebirth.
Answer:
The kinetic energy of the bullet is 5.4 × 10³ J
Explanation:
Hi there!
The equation of kinetic energy is the following:
KE = 1/2 · m · v²
Where:
KE = kinetic energy.
m = mass of the bullet.
v = speed of the bullet.
Let´s convert the mass unit to kg so that our result is in Joules:
64 g · ( 1 kg / 1000 g) = 0.064 kg
Then, the kinetic energy will be the following:
KE = 1/2 · 0.064 kg · (411 m/s)²
KE = 5.4 × 10³ J