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Homework Help: Finding velocity use energy conservation help

  1. Oct 10, 2009 #1
    A .145kg drop from sixth story building window. If each story is 2.5m tall, use energy conservation to find the rock velocity when it strikes the ground. (ignore air resistance)

    I have:
    mass .145kg
    h 2.5m each story
    2.5m * 6 = 15m (total height)
    gravity 9.8ms^2
    V=?
    I am confuse, what is energy conservation?
    please help me to start this
     
  2. jcsd
  3. Oct 10, 2009 #2
    mgh=0.5mv^2
    2gh=v^2
    v=sq root(2gh)
     
  4. Oct 13, 2009 #3
    thanks got it
     
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