Physics - Energy

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There are many different types of energy, but the main ones in physics are:

  • Kinetic Energy - 1/2mv^2
  • m = mass of the object
  • v = velocity

  • Gravitational Potential Energy - mgh
  • m = mass of the object
  • g = gravity (9.8/10 m/s^2)
  • h = height from the ground

  • Elastic Potential Energy - 1/2kx^2
  • k = the spring constant of the object
  • x = displacement (Stretch or compression)

    • An important concept in the energy unit is the Conversation of Energy

    This means that the starting energy in a system will be conserved throughout - E = E' - Intial energy in a system will equal to the same final amount of energy


  • Note - You can relate work to energy W = E

    • An example of an energy problem is trying to find the velocity of an object falling off of a cliff

    You would set the gravitational potential energy at the top of the cliff equal to kinetic energy at the bottom. This works because we know that the all the gravitational potential energy at the top of cliff will be conserved and converted into kinetic energy at the very bottom of the cliff.

    mgh = 1/2mv^2

    You would then rearrange the equation so that velocity is the only variable on one side to find the unknown.

    Note - Mass cancels out because mass will not change during the fall

    So the resulting equation would be √2gh = v