Solving work energy problems, with velocity and friction as givens.

[nickyak]

I need to solve a work energy equation for height that has initial velocity, final velocity, and work done by friction as the only givens, I don't want to give the full problem, but I can't even find how to do that in my physics book so any help would be appreciated. right now I have KE1+GPE1-Friction=KE2

 

[haruspex]

I don't want to give the full problem

You will at least need to disclose what it is that you are asked to find.

 

[PhizKid]

He needs to find the height. Can you make up a problem based on the given one? (Change all the numbers and wording)

 

[haruspex]

He needs to find the height.

Hmm.. yes, missed that.
Ok, so you have an equation regarding energy, and presumably you can write down expressions for KE etc. if only you knew the mass. Is that the problem? If so, just put in an unknown for mass and hope it cancels. (If the friction is proportional to the mass then it will.)

 

[Nickie]

+GPE2

To solve this type of problem, you will need to use the work-energy theorem, which states that the work done on an object is equal to the change in its kinetic energy. In this case, the work done by friction is equal to the negative of the change in kinetic energy. So your equation should look like this:

W = ΔKE + ΔPE - Ff

Where W is the work done on the object, ΔKE is the change in kinetic energy, ΔPE is the change in potential energy, and Ff is the force of friction. You can rearrange this equation to solve for the change in potential energy (ΔPE):

ΔPE = W - ΔKE + Ff

To find the final height (GPE2), you will need to use the equation for gravitational potential energy, which is:

GPE = mgh

Where m is the mass of the object, g is the acceleration due to gravity, and h is the height. You can rearrange this equation to solve for h:

h = GPE/mg

Now you can substitute this into the previous equation to solve for the final height:

GPE2 = (W - ΔKE + Ff)/mg

You can also use this equation to solve for the initial height (GPE1) by substituting the initial values for velocity and friction into the equation. I hope this helps and good luck with your problem-solving!