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So far am i correct

  1. Sep 17, 2007 #1
    idk if i did this correctly so far so here goes.

    The question states

    A large rubber ball (8.80 kg) is fired straight down from the roof of a building from a spring loaded mechanism that stored 987 J of elastic potential energy. The building roof is 14.0 meters above ground. The rubber bounces straight back up (noiselessly--don't ask how) back to a height of 9.5 meters. Assuming no heat is lost to the air around the ball, calculate the increase in temperature of the ball (Specific Heat of rubber is 1250 J/kgK

    What i did was:
    M= 8.80kg
    Spring Potential Energy= 987 J
    Building roof= 14.0 m
    The rubber bounces back up= 9.5 m
    Specific Heat of rubber is 1250 J/kgK

    1) I found the Change in Height= 14.0-9.5= 4.5m
    2) Then i used the gravitational potential energy formula which is
    (mass)(g)(the change in height)
    4)Gravitational Potential Energy= (8.80)(10)(4.5)
    gravitational potential energy= 396 J

    That is what i got for my gravitational potential energy then i used my spring potential energy which is 987 J and added that with 396 J and got 1383.
    I believe that the 1383 J is the heat and i should find the change in temp. am i right or am i wrong here
    Last edited: Sep 17, 2007
  2. jcsd
  3. Sep 17, 2007 #2


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    Looks good to me.
  4. Sep 18, 2007 #3


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    That is what we were getting at earlier. Why didn't you add that to your previous thread for this problem [ https://www.physicsforums.com/showthread.php?t=185227 ], rather than start another one?
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