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Work done

  • Thread starter cronusmin
  • Start date
10
0
Q: a man(40kg) walks up the stair of 3m high, how much work done by the man?

wat i think is, the man experienced the gravitational pull, so the man should get a work done of mgh=40*9.81*3 J, is this correct?

but the answer from the thermodynamic course tutorial Q is 0 J. why?

2nd Q: a man(40kg) walks up the stair of 3m high n walk down to floor again, how much work done by the man?

for this Q, i will answer 0 J, because the displacement is 0m.
 

Answers and Replies

458
0
I disagree with the answer for question 1. Is that the exact question, word for word?
 
10
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I disagree with the answer for question 1. Is that the exact question, word for word?
the question is correct, i copy this from a thermodynamics course student. when i get the answer is 0J, i also felt surprised. how should it b 0J i think. is that the frame of reference the thermodynamics course consider is not same as physics course?
 
10
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I disagree with the answer for question 1. Is that the exact question, word for word?
besides tat, the lecturer for the thermodynamics course is a professor in that subject...
any idea for that?
 
454
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Only work done on something else counts. The man has pushed against the stairs, but those haven't moved, so he has added no energy to anything else.
 
10
0
Only work done on something else counts. The man has pushed against the stairs, but those haven't moved, so he has added no energy to anything else.
in case the Q is asking for the work done by the man, so any relation for the man pushing on the stair?
 

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