Forces with just energy levels

[Pengwuino]

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 im 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.

[HallsofIvy]

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.

[Pengwuino]

Wait so it would only determine hte average force? I wouldn't think that a leg pushing up someone on stairs is exactly a consistant force.

[jtbell]

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.