Energy Conversion: Where Does the Energy Come From?

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Discussion Overview

The discussion revolves around the energy conversion processes involved when a helium balloon rises. Participants explore the sources of energy that contribute to the balloon's gain in gravitational potential energy (Ep) and kinetic energy (Ek) during ascent.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant suggests that the energy for the balloon's ascent comes from the density differential between the helium and the surrounding air, which displaces air molecules and converts their potential energy into kinetic energy that propels the balloon.
  • Another participant agrees with the initial claim, reinforcing the idea that the energy is derived from the displacement of air molecules.
  • A different perspective is introduced, stating that a helium balloon actually loses potential energy during its ascent while gaining altitude, and that energy is expended when pulling the balloon down, which is then converted into gravitational potential energy as the balloon rises.
  • This perspective emphasizes that while the balloon gains height and potential energy, the surrounding air loses potential energy, suggesting a broader system view of energy conservation.

Areas of Agreement / Disagreement

Participants express disagreement regarding whether the balloon gains or loses potential energy during ascent. Some argue that it gains potential energy, while others assert that it loses potential energy, indicating that multiple competing views remain unresolved.

Contextual Notes

There are unresolved assumptions regarding the definitions of energy types and the system boundaries considered in the discussion. The interplay between the balloon and the surrounding air is not fully clarified, leading to differing interpretations of energy conversion.

elitewarr
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When a helium balloon rises from rest, it gains Ep, at the same time, it gains Ek. So where does these energy come from?
My guess would be due to density differential, the balloon will rise and this will displace the air molecules which will fall to take the place of the balloon. This reduction of Ep of air molecules is converted to Ek, which pushes the balloon, causing work done on the balloon, thus giving it energy.
What do you think?
Thanks.
 
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elitewarr said:
When a helium balloon rises from rest, it gains Ep, at the same time, it gains Ek. So where does these energy come from?
My guess would be due to density differential, the balloon will rise and this will displace the air molecules which will fall to take the place of the balloon. This reduction of Ep of air molecules is converted to Ek, which pushes the balloon, causing work done on the balloon, thus giving it energy.
You are exactly correct.
 
Thank you for the fast reply :D
 
DaleSpam said:
You are exactly correct.

Do you mean that a helium balloon gains Ep on ascent... No.

A helium balloon looses Ep during it's ascent and gains altitude.

E.g. By pulling a balloon down you expend energy while the balloon gains that energy as Ep.
 
Lok said:
Do you mean that a helium balloon gains Ep on ascent... No.

A helium balloon looses Ep during it's ascent and gains altitude.

E.g. By pulling a balloon down you expend energy while the balloon gains that energy as Ep.
The balloon (treated in isolation) gains Gravitational Potential Energy - because it's higher - but the total system - including the air around it, loses Ep, for the reason given above.
 

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