Astronaut and Satellite Separation Speeds

AI Thread Summary
An astronaut with a mass of 74 kg pushes off a satellite of 420 kg with a force of 120 N for 0.82 seconds. The initial calculations included the astronaut's weight, which is irrelevant in space, leading to confusion in determining acceleration and velocity. The correct approach focuses solely on the force applied and the astronaut's mass to calculate acceleration. After clarifying the method, the astronaut successfully determines the correct speed after separation. This discussion emphasizes the importance of isolating relevant forces in physics problems.
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Homework Statement



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.

Homework Equations



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

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?
 
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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.
 
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How much does 120N make 74kg accelerate? Thats all you need to consider to get the accelaration of the astronaut.
 
Alright! I got it! Thank you so much for your help.
 
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