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Basic question on F=ma

  1. Oct 21, 2007 #1
    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:
    F/M =A
    -180/75 =A OR -180/75=A
    -2.4 m/(s^2) und =A

    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. jcsd
  3. Oct 21, 2007 #2
    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.
  4. Oct 21, 2007 #3
    Thanks, I just needed someone to make sure I wasn't being stupid.
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