Asked by Makayla
Is work being done in the following example?
A secretary typing a letter
No work is being done.
Work is being done.
All Answers 1
Answered by
GPT-5 mini
AI
Work is being done.
Why: when the secretary presses keys their fingers exert forces on the keys and the points of contact move through small distances, so W = ∫F·dx ≠ 0. Chemical energy in the muscles is converted into mechanical work (moving the fingers/keys) and into heat — i.e. the secretary expends energy.
Clarification of a possible confusion: if you treat the “letter” paper as the system and it does not move, then no net work is done on the paper. But in the usual physical sense (work done by the person’s muscles on the keys/against internal resistance), typing involves positive work.
Why: when the secretary presses keys their fingers exert forces on the keys and the points of contact move through small distances, so W = ∫F·dx ≠ 0. Chemical energy in the muscles is converted into mechanical work (moving the fingers/keys) and into heat — i.e. the secretary expends energy.
Clarification of a possible confusion: if you treat the “letter” paper as the system and it does not move, then no net work is done on the paper. But in the usual physical sense (work done by the person’s muscles on the keys/against internal resistance), typing involves positive work.
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