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Homework Help: Work and energy

  1. Dec 20, 2011 #1

    I need help in work and energy

    I Attached the File


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  2. jcsd
  3. Dec 20, 2011 #2
    I need some help to help you. Would you mind posting some of the ideas that come to your mind in how to solve this. There are three types of energy in this problem: kinetic, gravitation potential, and spring potential. Which do you think are relevant? Where are the possible places that the energy can be?
  4. Dec 20, 2011 #3
    I meaning kinetic energy and spring potential
    The cube is to striking down the spring
  5. Dec 20, 2011 #4
    Has the question specified that there is no frictional force or drag forces? That is, is all gravitational potential energy being converted to kinetic and all kinetic being converted to spring potential?
  6. Dec 20, 2011 #5
    yes I believe that is what he means. What I meant to say is that do you see a role for kinetic energy in this question?

    Initially, it is evaluated when the block is at rest. It then asks to find the maximum compression; when the block is also at rest.
  7. Dec 20, 2011 #6
    No, I don't see a role for Kinetic energy, I was just going through the steps.

    If you mean how much force it would be if it was just placed onto the spring, at that angle, then it would be weight of the object, in the horizontal direction. So, you would have to resolve the forces, then solve as a usual spring compression: F=kx.

    If we are talking about letting it lose, then calculating it, it would be the change in gravitational potential is equal to the elastic potential energy acting on the spring, as it is all converted.
  8. Dec 20, 2011 #7


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    Moderator's note: let's let the OP post with an update on his/her progress before offering further help or hints.
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