Momentum of Astronaut and Satellite

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Homework Statement


A 92-kg astronaut and a 1200-kg satellite are at rest relative to the space shuttle. The astronaut pushes on the satellite, giving it a speed of 0.14 m/s directly away from the shuttle. Seven-and-a-half seconds later the astronaut comes into contact with the shuttle. What was the initial distance from the shuttle to the astronaut?


Homework Equations


(m1)(v1) = (m2)(v2)


The Attempt at a Solution


(1200)(14)=(92)(v2)

(v2)=182.61

d= vt

d=182.61*7

d=1278.26 m (Is this right?)
 

Answers and Replies

  • #2
DaveC426913
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d=1278.26 m (Is this right?)
What does your gut tell you about that answer? How far is that?

Does that seem right - considering the velocity and time involved?

If no, go back and check all your numbers.
And your decimals.
 
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  • #3
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What does your gut tell you about that answer? How far is that?

Does that seem right - considering the velocity and time involved?

If no, go back and check all your numbers.
And your decimals.

Oh, wow, another careless mistake like on my previous question...So, besides the "decimal manipulation", are there any other errors like lack of vectors (negative and positive). I am having a dilemma on whether to make v1 negative since it's going the opposite direction.
 
  • #4
DaveC426913
Gold Member
19,294
2,778
Oh, wow, another careless mistake like on my previous question...So, besides the "decimal manipulation", are there any other errors like lack of vectors (negative and positive). I am having a dilemma on whether to make v1 negative since it's going the opposite direction.
There's also a delta-t issue.

As for neg and psotive, I suppose it depends on how rigorous you need your work to be. If you just need to supply the value, it'll work out.
 
  • #5
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There's also a delta-t issue.

As for neg and psotive, I suppose it depends on how rigorous you need your work to be. If you just need to supply the value, it'll work out.

I guess I just need the scaler quantity. Thanks for notcing my Δt error also. I need to read the questions more carefully.

By the way, I got my answer to be 13.725 meters if someone can confirm.
 
  • #6
DaveC426913
Gold Member
19,294
2,778
I guess I just need the scaler quantity. Thanks for notcing my Δt error also. I need to read the questions more carefully.

By the way, I got my answer to be 13.725 meters if someone can confirm.
Hm. I get 13.7 - and that's rounded up from 13.695.

Ah. I see. Sig digs.
I did 1.826*7.5.
You did 1.83*7.5 = 13.725.

Well, it still rounds to 13.7.
 
  • #7
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Hm. I get 13.7 - and that's rounded up from 13.696.

It's just my lazy rounding error. Thanks for the confirmation!
 

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