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Everyday connections and other things to discuss.

  1. Jan 22, 2006 #1
    A few questions i don't understand on the huge holiday assignment for the three day weekend.

    1) Why are most mountain roads designed so that they weave back and forth with a gradual slope rather than going straight uphill.

    2) What are the work-energy transformations involved in throwing a ball upward.

    3) What is the work-energy conversion which occurs when a crane lifts a heavy crate from the ground to the top of a three-story building?

    4) What happendes to the energy when a moving car hits a brick wall and comes to rest?

    5) What happens to the work expended by a boy pulling a sled across the ice of a frozen pond?

    6) What has happened to the energy of a ball rolling across the floor as it comes to a stop.

    If you could answer any of these I would greatly appreciate it. Some of you will think that I am asking for last minute homework help. The answer is I am not. I am just interested in the answers to the questions. Thanks again.
  2. jcsd
  3. Jan 22, 2006 #2

    Claude Bile

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    Science Advisor

    Help us help you by showing us exactly what it is you are stuck on. This will alow us to identify where the gaps in your knowledge are, and hopefully allow us to fill them.

  4. Jan 22, 2006 #3
    I know about Potential Energy and Kinetic Energy but I don't know how the both of them go together

    For question number 6, i think the kinetic energy has turned into heat due to friction of the floor on the ball?

    For question number 3, at the ground level, the crate has all Kinetic Energy and no potential energy. As the crane lifts the crate up, more Potential Energy is gradually gained until it reaches the third floor where it has all Potential Energy and no Kinetic Energy. Is this right or wrong?
    Last edited: Jan 22, 2006
  5. Jan 23, 2006 #4


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    Homework Helper

    for Q'n #3, the crate never has very much Kinetic Energy since it will never be moving fast (Kinetic means motional). What type of Force has potential to do Work when the crate is at the top? Where did the Energy come from that allowed the crane to do Work (that is, to lift the crate)?
  6. Jan 23, 2006 #5
    ummm you can forget about it now. I already turned it in with that answer on it. No problems. Thanks for helping though. I might hang around here sometimes so be on the lookout for more questions. Take care all.
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