Work done on a stationary bicycle?

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    Bicycle Work Work done
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Discussion Overview

The discussion revolves around the concept of work done while cycling on a stationary bicycle. Participants explore the definitions of work, energy conversion, and the implications of resistance forces in both stationary and regular cycling contexts.

Discussion Character

  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants question whether work is being done on a stationary bike since work is defined as Force multiplied by distance, and they argue that there is no distance involved.
  • Others propose that while cycling, force is generated to turn the pedals against a reactive force, suggesting that work is indeed being done despite the bike being stationary.
  • One participant mentions that stationary bikes convert the energy produced into heat, referencing a formula for work that includes mass, specific heat capacity, and temperature change.
  • There is confusion about the relationship between work and distance, with participants noting that in regular cycling, work is calculated using Force times distance without accounting for temperature changes.
  • Some argue that energy is conserved and transformed from one form to another, with total force in cycling accounting for various resistive forces like air resistance and rolling resistance.
  • Another participant highlights the importance of understanding the contributions of different forces, such as drag and rolling resistance, to the total work done.

Areas of Agreement / Disagreement

The discussion remains unresolved, with participants expressing differing views on the definition of work in the context of stationary cycling and the relevance of distance in the calculation of work.

Contextual Notes

Participants express uncertainty regarding the definitions of work and energy, the role of resistive forces, and the applicability of different equations in various cycling scenarios.

vizakenjack
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So when someone is simply cycling on a stationary bike, is that person doing any work? Because work is Force * distance. But there's no distance here, right?

Is work simply the energy then?
 
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vizakenjack said:
So when someone is simply cycling on a stationary bike, is that person doing any work? Because work is Force * distance. But there's no distance here, right?

Is work simply the energy then?
You are generating force with your legs to turn the pedals & crankshaft against a reactive force. Stationary bikes are designed to have a configurable resistance that they offer to your pedaling. :smile:
 
Stationary exercise bikes usually turn the energy you produce into heat, perhaps heating a mass of air...

Work = mass * specific heat capacity * temperature change.
 
CWatters said:
Work = mass * specific heat capacity * temperature change.
But I thought work had to have distance?

So how come, when you cycle a regular bicycle on a road, you don't account for temperature change? You just do F*distance
 
vizakenjack said:
But I thought work had to have distance?
The pedals are moving.
 
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vizakenjack said:
But I thought work had to have distance?

So how come, when you cycle a regular bicycle on a road, you don't account for temperature change? You just do F*distance

Energy is always conserved, its just converted from one form to another. The equations you can use to calculate the flow of energy in a system depends on the form of energy at that point in the system.

When you cycle a regular bike some of the total force is due to air resistance. Stirring the air heats it up. No need to account for this separately because its already included in the total force. Another part of the total force is due to rolling resistance an that heats the tyres. Again no need to account for that separately because its also included in the total force.
 
Clearly there are times when you would like to know what fraction of force * distance is due to drag, rolling resistance, bearing friction etc and account for all the components separately.
 

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