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Conservation of energy problem

  1. Mar 14, 2009 #1
    1. The problem statement, all variables and given/known data
    A 2.5 kg block of ice at a temperature of zero degrees celcius and an initial speed of 5.7 m/s slides across a level floor. If 3.3 x 105 J are required to melt 1 kg of ice, how much ice melts, assuming that the initial kinetic energy of the ice block is entirely converted to the ice's internal energy?


    2. Relevant equations
    I think I need to use PE + KE + U = 0


    3. The attempt at a solution
    I have no idea where to even begin :(
     
  2. jcsd
  3. Mar 14, 2009 #2
    Well the formula for kinetic energy of a body is KE = .5mv2. So how much kinetic energy do we have in the block at the start? If you assume all of that gets transferred into heat energy how much ice did it melt?
     
  4. Mar 14, 2009 #3
    Ok, so I used KE = .5mv2 and found that the ice has an initial KE of 41 J. Then I did 41 / 3.3 x 105 and I concluded that .0000124 kg of ice melted. Is this correct?
     
  5. Mar 14, 2009 #4
    Sounds correct to me.
     
  6. Mar 14, 2009 #5
    Great, thanks a lot.
     
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