Chemical energy in the runner's body

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Homework Help Overview

The discussion revolves around a test question regarding the transformation of chemical energy in a runner's body while running at a constant speed on level ground. Participants are exploring the relationship between chemical energy and its conversion to other forms of energy, specifically thermal, potential, and kinetic energy.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are questioning the reasoning behind the correct answer being thermal energy instead of kinetic energy, with some noting that human energy often dissipates as heat. Others are discussing the implications of running on level ground, which eliminates potential energy as a factor.

Discussion Status

The discussion is active, with various interpretations being explored. Some participants suggest that both thermal and kinetic energy transformations are relevant, while others emphasize the need for clarity on the question's intent. There is no explicit consensus, but multiple viewpoints are being considered.

Contextual Notes

There is a focus on the nature of energy transformations in a biological context, with references to muscular movement and energy dissipation. Participants are also noting the ambiguity in the question regarding changes in kinetic energy.

courtneylane8
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So I got back a test and one of the questions was the following: A person is running at a constant speed on level ground. Chemical energy in the runner's body is being transformed to other forms of energy: most of the chemical energy is transformed to?
a. thermal energy
b. potential energy
c. kinetic energy

I chose kinetic energy but the correct answer is thermal. Do anyone know how to explain why?
 
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I probably would have chosen kinetic as well, but thermal makes sense, because a lot of human's energy is wasted by becoming heat rather than kinetic.
 


courtneylane8 said:
So I got back a test and one of the questions was the following: A person is running at a constant speed on level ground. Chemical energy in the runner's body is being transformed to other forms of energy: most of the chemical energy is transformed to?
a. thermal energy
b. potential energy
c. kinetic energy

I chose kinetic energy but the correct answer is thermal. Do anyone know how to explain why?

Well ... it's not up hill ... there goes potential energy as a possibility.
There is no change in velocity ... so there goes any change in kinetic energy.
 


That is a bad question. There are various forms of energy in that given situation. Both A and C are correct.

There's heat transfer going on between the body and the ambient environment. However, there's electrical energy, kinetic energy, and chemical energy involved, as well.

Muscular movement is a combination of electrical signals and chemical motion (Through Fickian diffusion and biological motors).

Muscular movement results in kinetic energy.


EDIT: But Lowly, it doesn't say if there's change in KE. It just says what is the energy being transformed to. The change in KE could be 0, but there's KE.
 


Thank you all!
 


womfalcs3 said:
EDIT: But Lowly, it doesn't say if there's change in KE. It just says what is the energy being transformed to. The change in KE could be 0, but there's KE.

For this kind of question I don't think it matters. Whatever the internal energies of the system, the pumping of the arms and pounding of the legs, the impact of the shoes, muscles pulling tendons and bones about, the kinetic energy converts to thermal energy readily enough. For the kind of introductory question it is, I'm sure there is no intent to get esoteric about chemical/biological processes.

Besides, I suspect when viewed over a complete stride it is mostly thermal after accounting for the energy state changes.
 

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