Man Walks Up Stairs: Work Done?

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Homework Help Overview

The discussion revolves around the concept of work done in physics, specifically in the context of a man walking up and down stairs. The problem involves calculating the work done against gravitational forces and the implications of displacement in the context of thermodynamics.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the calculation of work done using the formula mgh and question the validity of an answer that states the work done is 0 J. There is also discussion about the implications of displacement being zero when the man walks back down.

Discussion Status

There is an ongoing debate regarding the interpretation of the problem and the differing answers provided by physics and thermodynamics perspectives. Some participants express confusion about the reasoning behind the 0 J answer and question the frame of reference used in the thermodynamics course.

Contextual Notes

Participants note that the question was sourced from a thermodynamics course, which may have different assumptions or interpretations compared to standard physics problems. The discussion highlights the importance of understanding the context in which work is defined.

cronusmin
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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.
 
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I disagree with the answer for question 1. Is that the exact question, word for word?
 
Snazzy said:
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?
 
Snazzy said:
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?
 
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.
 
kamerling said:
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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