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Homework Help: Skateboarder with a mass of 150kg

  1. Sep 28, 2012 #1
    A skateboarder with a mass of 150 kg is traveling at a final velocity of 13m/s and collides with a steel dumpster. The dumpster does not move. The skateboarder comes to a stop at 0.25 seconds. What is his rate of acceleration as he stops? How much force does he exert on the dumpster?

    Can someone help me please.
  2. jcsd
  3. Sep 28, 2012 #2
    Can you write down an equation for the relationship between time, acceleration and change in velocity?
  4. Sep 28, 2012 #3
    Initial velocity= 13ms^-1
    Final velocity= 0ms^-1
    Time= 0.25s

    A) Rate of acceleration = (V-U)/T = (0-13)/0.25 = -52ms^-2

    B) Force exerted on the dumpster= F= (MV)/ T = (150*13)/0.25 = 7800N

    I think?
  5. Sep 28, 2012 #4
    That looks correct to me! Average acceleration is change in velocity divided by change in time. Force exerted is equal to the change in momentum.
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