# An astronaut and a satellite

1. Apr 7, 2007

### meran

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

An astronaut of mass 74 kg pushes off a satellite of mass 420 kg, exerting a force of 120 N for the 0.82 s they are in contact.

2. Relevant equations

What is the speed of the astronaut after they have separated?
What is the speed of the satellite after they have separated?

3. The attempt at a solution

The astronaut's weight is -726 N. If he were to push with 120 N, the combined forces would equal -734.8 N. Therefore, from F=ma, acceleration would be -9.93 m/s/s and veloctiy (-9.93=v/.82) would equal -8.14 m/s. However, that is not the correct answer. I have a feeling something in my initial set up is wrong. Any ideas?

2. Apr 7, 2007

### hage567

The astronaut's weight has nothing to do with it (he's in space!). You only need to consider the masses. I don't get where you got the -734.8 N from. There is only the one force acting. Other than that, I think you are on the right track.

Last edited: Apr 7, 2007
3. Apr 7, 2007

### eigenglue

How much does 120N make 74kg accelerate? Thats all you need to consider to get the accelaration of the astronaut.

4. Apr 7, 2007

### meran

Alright! I got it! Thank you so much for your help.