Work done by non conservative force

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SUMMARY

The discussion centers on the calculation of work done by non-conservative forces using the area under the Force vs. Displacement curve. It is established that while the area can represent work in one-dimensional scenarios, this approach fails in multi-dimensional cases where the work is determined by a curvilinear integral. The distinction between conservative and non-conservative forces is clarified, emphasizing that non-conservative forces yield different work values for different paths between the same points, negating the utility of a simple area calculation.

PREREQUISITES
  • Understanding of Force vs. Displacement graphs
  • Knowledge of conservative and non-conservative forces
  • Familiarity with curvilinear integrals in physics
  • Basic principles of thermodynamics, particularly PV curves
NEXT STEPS
  • Study the concept of conservative vs. non-conservative forces in detail
  • Learn about curvilinear integrals and their applications in physics
  • Explore the calculation of work done in thermodynamic cycles using PV diagrams
  • Investigate one-dimensional vs. multi-dimensional work calculations
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Students of physics, educators teaching mechanics, and professionals involved in thermodynamics or mechanical engineering will benefit from this discussion.

pagmax
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If the total work done is calculated using the area of the closed curve (Force vs Displacement), then the formulation doesn’t care if the force is conservative or not. Is that right? For instance, if I understand it right, spring force is a conservative force and hence work done by the spring in bringing a mass back to its original position should be zero. However, if we are able to plot spring force against displacement, we surely have a non-zero area under it.
My essentially question is can the work done by a non-conservative can be calculated by area under Force vs Displacement curve? Is that right? So when we calculate work done by a gas in piston as area under PV curve of the thermodynamic cycle, this is because gas force is a non-conservative force?
 
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hhhmmm...I don't remember my physiscs that well and what the difference between conservative and non-conservative force is...

...but are you sure you have a resulting work at the end? I mean, it may seem like there is area under the curve, but don't forget that your distance travel on the way back is of opposite sign as when going forward, and so, if you integrate that "area under the curve" is going to cancel out ...

does this make sense?
 
pagmax said:
If the total work done is calculated using the area of the closed curve (Force vs Displacement), then the formulation doesn’t care if the force is conservative or not. Is that right?

I think you have a misunderstanding. The work would be the area in the coordinate plane Force vs displacement. But, this is true only in a one-dimensional case. In more than one dimension, the force is a curvilinear integral:
<br /> W = \int_{C}{\mathbf{F} \cdot d\mathbf{x}} = \int_{C}{F_{x} \, dx + F_{y} \, dy + F_{z} \, dz}<br />
The force is non-conservative if the work is different for different contours in three-dimensional space between the same two points. There is no area that you can construct in this case.
 

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