How far apart are the astronaut and the satellite after 1.40 min?

Question

An 79.0 kg spacewalking astronaut pushes off a 660 kg satellite, exerting a 120 N force for the 0.420 s it takes him to straighten his arms.

Answer 1

The 120N force on the astronaut accelerates him/her at a rate of 120/79 m/s^2. In 0.42 s, this would accelerate the astronaut to a velocity of 0.42 (120/79) m/s.

Similarly, the satellite accelerates in the opposite direction to a velocity of 0.42 (120/660) m/s

The relative velocity of the astronaut and the satellite is
0.42 (120) (1/79 + 1/660) m/s

Multiply this by 84 seconds (which is equivalent to 1.4 min), and you'll have the requested distance.
Note: This is the distance the astronaut will be from the satellite IN ADDITION TO the length of the astronaut's arms. We started counting the time when the astronaut had straightened his/her arms.