Homework Help: Newton III problem involving two objects in space

1. Mar 7, 2009

angotta

1. The problem statement, all variables and given/known data

An 93.0 spacewalking astronaut pushes off a 620 satellite, exerting a 120 force for the 0.470 it takes him to straighten his arms

2. Relevant equations

FA on S=FS on A
Xf=Xi+Vi$$\Delta$$t+1/2a($$\Delta$$t)2

Those are the equations I think I use. And initial velocity should be zero, also for time I subtracted the time of the astronaut pushing off the total time

3. The attempt at a solution

I found the acceleration of the astronaut to be 1.29
and the acceleration of the satellite to be 0.194

Then I tried to fill those into the kinematic equations but I got a way large answer. I just need some guidance on where to start and such.

2. Mar 7, 2009

Staff: Mentor

Please state the problem exactly as given. What are you asked to find?

3. Mar 7, 2009

angotta

Im sorry we are asked to find how far apart are the astronaut and the satellite are after 1.50 ?

4. Mar 7, 2009

Staff: Mentor

Good. Those are the accelerations during the push. Now use kinematics to solve for how fast they are going at the end of the push.

(Once the push is over, they move at constant speed. Then you can calculate how far they get from the starting point.)

5. Mar 7, 2009

angotta

Thank you I found the answer to be 62.8 m which was correct.

6. Mar 7, 2009

lubuntu

Ah Newton the Third, his laws are much less well known than his grandfather's though ;)