Muscles opperating with efficiency of 18%

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Homework Help Overview

The problem context involves calculating the amount of chemical energy expended by a person ascending stairs, given the efficiency of muscle energy conversion. The subject area pertains to physics, specifically potential energy and efficiency in biological systems.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the relevance of the 18% efficiency in relation to the potential energy calculated. There is an exploration of how to relate the potential energy gained to the total chemical energy required.

Discussion Status

The discussion includes various attempts to calculate the required chemical energy, with participants providing different numerical estimates. Some guidance on the relationship between potential energy and chemical energy has been offered, but there is no explicit consensus on the final answer.

Contextual Notes

Participants are working under the assumption that the efficiency of muscle energy conversion is fixed at 18%, and they are questioning how this impacts their calculations. There is also a mention of potential confusion regarding the application of this efficiency to the problem.

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Homework Statement

Muscles operate with an efficiency of about 18.0 percent in converting stored chemical energy into work. How much chemical energy will be expended by a 63.6 kg person in the process of ascending several flights of stairs to a height of 21.0m?

Homework Equations

pe= mgh(initial)



The Attempt at a Solution

pe=13088.88 J i wasnt sure if the 18% had anything to do with the problem or not
 
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The 18% are relevant.

13088.88 J is the potential energy the person gains. However, the question asks for the chemical energy.

Muscles can convert this chemical energy into work with 18% efficiency - if you expend 100 J of chemical energy, you can gain 18 J of potential energy (at least according to this problem). How much chemical energy to you need to gain 13088.88 J of potential energy?
 
i think 2355.10??
 
no wait i got 72716 J...i think that's right then
 
yup that works thanks!
 

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