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Homework Help: Ball dropped from building - find speed and kinetic energy

  1. Nov 14, 2007 #1
    An 0.50kg mass is droped from the top of a 20m tall building. Immediately before hitting the sidewalk

    a) the speed of the ball is ?
    b) The KE of the ball half way down will be

  2. jcsd
  3. Nov 14, 2007 #2
    What's being conserved here, and what equation should you use? Any thoughts?
  4. Nov 14, 2007 #3
    Basically right now im at this point
    vf= (2*9.8* 20) the sqaure root of this answer .

    Would that tell me the final speed
  5. Nov 14, 2007 #4
    Yes, that is correct.
  6. Nov 14, 2007 #5
    So for part b

    vf= 2*9.8*10 and the sqaure root of this
    = 14

    Is this part right.
  7. Nov 14, 2007 #6
    Well, that is the speed that you would plug into the equation for kinetic energy, but yes, you are correct.
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