Mechanical Energy in a parachute

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Homework Help Overview

The discussion revolves around the mechanical energy of a parachuter-parachute-Earth system, particularly in the context of air resistance. The original poster seeks clarification on whether the mechanical energy remains constant when considering the entire system, rather than just the parachuter.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the conservation of mechanical energy in the presence of air resistance, questioning how energy transformations occur within the system. Some participants suggest that energy is transformed into heat, while others consider scenarios without air drag.

Discussion Status

The discussion is active, with participants expressing differing views on energy conservation. Some have provided reasoning related to energy transformation and the effects of air resistance, while others are still contemplating the implications of these factors on the overall mechanical energy of the system.

Contextual Notes

Participants are considering the effects of air resistance and the transformation of energy into thermal energy, which may impact their understanding of mechanical energy conservation. There is an emphasis on analyzing the system as a whole rather than in isolation.

grizzlyjoker
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Given an parachuter and the system parachuter-parachute-Earth and taking in account the resistance of the air, my question is: is the mechanical energy of the system (parachuter.parachute.Earth) a constant, please explain. And please don't talk just about the parachuter because I wan't to know about the parachuter and Earth as one system.
Thank you in advance.
 
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What do you think?
 
I think it isn't conserved because of the transformation of that energy in heat
 
grizzlyjoker said:
I think it isn't conserved because of the transformation of that energy in heat
Good. You've answered your own question.

If the parachutist jumped in a vacuum, his kinetic energy would increase as the gravitational PE of the system decreased. Since there'd be no dissipative forces, the total mechanical energy would remain constant.

But with air drag present, much of his kinetic energy is transformed into random motion of the air--"thermal" energy. (The air gets stirred up, it and the parachute get warmer.) So the net mechanical energy of the system decreases.
 

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