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Homework Help: Types of energy

  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

    2. Relevant equations


    3. The attempt at a solution

    I think it is kinetic energy. But I am confused on the differences of types of energies.
  2. jcsd
  3. Mar 27, 2014 #2
    Why do you think it has kinetic energy?
  4. Mar 30, 2014 #3
    Potential Energy (Gravitational potential energy)
    It does not have Kinetic energy because it is not in motion in your frame. (K.E = 1/2mv^2)

    It does have Potential energy since you have done work (put energy into the system) in lifting the eraser up. That energy is stored as potential energy P.E = mgh ready to be released as kinetic as soon as you let the eraser go.
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