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Homework Help: Different types of energy: kinetic vs potential vs

  1. Mar 27, 2014 #1
    1. The problem statement, all variables and given/known data

    What type of energy does a blackboard eraser have when I hold it steady three feet about the ground?

    a. potential energy
    b. kinetic energy
    c. electrical energy
    d. spring elastic energy

    I think it is kinetic energy. But I am confused on the differences of types of energies.
  2. jcsd
  3. Mar 27, 2014 #2
    Kinetic energy is what an object has when it is moving, so if you hold the eraser steady, it's kinetic energy will be equal to zero.

    Think about what would happen if you let go of the eraser.
  4. Mar 28, 2014 #3
    Tell us what do you know about the 4 types of energies.
  5. Mar 28, 2014 #4
    It's potential energy while it is still. and then kinetic if you start moving the eraser.
  6. Mar 28, 2014 #5
    It's potential only if it has a relative height associated with it. For example, if the reference point is the floor and the eraser is held still on the floor then the kinetic energy is zero but the potential energy is also zero.

    So being still is not itself the reason for something having potential energy. Think of potential energy as having the potential to transform into kinetic energy.
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