# Homework Help: Basic question on F=ma

1. Oct 21, 2007

### Oliviam12

I know this is rather basic, but some how I confused myself... The question is:

An astronaut of mass 75 kg performs repair work on the 1700 kg satellite, while floating right next to it. He exerts a force of 180 N on the satellite.
What is his acceleration as a consequence of this, and what is the acceleration
of the satellite?

Ok, I know the force acting on the satellite is 180 N and the force acting on the astronaut is -180 N, because newtons 3rd law (F=-F)

Now here is my main question. I know to solve I need to Use F=MA for both the astronaut and satellite but, is their mass relevant?

So is it:
Astronaut:
F/M =A
-180/75 =A OR -180/75=A
-2.4 m/(s^2) und =A

Satellite:
180/1700 =A or 180/0= A
.105882 m/s^2 =A und=A

Sorry, for asking such a duh! kind of question but, I am taking AP Physics as an online course and the grading policy is crazy and the teacher and course mat'ls are useless.

Last edited: Oct 21, 2007
2. Oct 21, 2007

### MrXow

Yes, their mass is relevant. The astronaut will move away faster than the satellite will. The formulas for the acceleration that you have are correct.

3. Oct 21, 2007

### Oliviam12

Thanks, I just needed someone to make sure I wasn't being stupid.