# Energy Problem Involving KE and PE

## Homework Statement

I attached a link with the description of the problem attached to it.

## Homework Equations

PE=m*g*h
KE=1/2mv^2
Work=F*d

Total Mechanical Energy= KEinitial+PEinitial+Workexternal

## The Attempt at a Solution

I was totally confused by this problem because the mass was not given to me. I'll show what I did:

KE=9*m/2-----top of hill
PE=245*m----top of hill

At bottom of hill PE is zero because of no height, therefore KEinitial+PEinitial=KEfinal

The problem wants to find the instantaneous velocity at the bottom of the hill. I am totally confused on how to solve this without the mass given though, help very greatly appreciated. If the attachment doesn't work or is too small, tell me and I will write out that question. I just need some boost to get me goin on this problem.

#### Attachments

• PHYSICS PRINT SCREEN PROBS.doc
173 KB · Views: 117

tiny-tim
Homework Helper
hi jcfor3ver!

(try using the X2 and X2 icons just above the Reply box )
I was totally confused by this problem because the mass was not given to me.

At bottom of hill PE is zero because of no height, therefore KEinitial+PEinitial=KEfinal

The problem wants to find the instantaneous velocity at the bottom of the hill.

that equation should give you the velocity: just call the mass "m", and you'll find it'll cancel out (because it's in everything! )