Using GPE and KE to find speed

  • Thread starter swede5670
  • Start date
  • #1
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Homework Statement


After falling 5m a rock has a velocity of v. What is the total distance the rock must fall to get a speed of 2v?


Homework Equations


GPE=mgh
Ke=1/2mv^2

The Attempt at a Solution


Should I set both equations equal to each other? I'm not even sure how to begin this one.
 

Answers and Replies

  • #2
LowlyPion
Homework Helper
3,097
5
You can do it that way. Note that v = (2*g*h)½

If v ∝ h½ ...

... how much then do you need to increase the height to get a doubling of speed?
 

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