Can Force Be Determined Solely from Kinetic Energy and Displacement?

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Discussion Overview

The discussion revolves around whether it is possible to determine the force applied to an object solely from its final kinetic energy and displacement. Participants explore the relationship between work, force, and energy, particularly in the context of moving up stairs.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions if force can be determined from final kinetic energy and displacement, recalling an equation related to work.
  • Another participant states that work equals force times distance and suggests that if all forces are conservative, one could calculate average force by equating changes in potential and kinetic energy to work done.
  • A different participant points out that the force exerted while climbing stairs is likely not consistent, implying that average force may not capture the true nature of the force applied.
  • It is noted that without information on how force varies with position, only the average force can be determined, as multiple force variations can lead to the same change in kinetic energy.

Areas of Agreement / Disagreement

Participants generally agree that only average force can be determined without additional information about force variation, but there is a debate about the implications of this limitation and the nature of forces involved.

Contextual Notes

The discussion highlights limitations in determining specific forces without knowledge of their variation over distance, as well as the assumption that forces may not be conservative.

Pengwuino
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Hey guys I was wondering something probably very simple.

Would I be able to determine the force something has been applying if I simply know its final kinetic energy and displacement?

And I remember this one equation where something = Integral of F * dx. I swear I am forgetting everything I ever learned :( I was running up the stairs to get to class and i started thinken if there was a way to determine what kinda force i was exerting in order ot get up those stairs.
 
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Work= force times distance. Assuming all forces are conservative, you could calculate the total change in both potential energy and kinetic energy, set that equal to force times distance and solve for (average) force.

Of course, if there are forces that are not conservative, then there is no way to find the force.
 
Wait so it would only determine hte average force? I wouldn't think that a leg pushing up someone on stairs is exactly a consistent force.
 
If you don't have any information at all about how the force varies with position, all you can do is find the average force. There are many ways the force can vary and still produce the same net change in kinetic energy.
 

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