Energy Problem Involving KE and PE

  • Thread starter jcfor3ver
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  • #1
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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

Answers and Replies

  • #2
tiny-tim
Science Advisor
Homework Helper
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hi jcfor3ver! :smile:

(try using the X2 and X2 icons just above the Reply box :wink:)
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.

(i can't read your attachment, but anyway …)

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! :wink:)
 

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