Conservation of Energy

When an object is both translating and rotating, we need to incorporate the kinetic energy of both of these motions, K = ½ mv2 + ½ Iω2, into energy conservation.

With this more complete form of kinetic energy, we can still apply: DOEL for solving energy conservation problems.

  1. Define/draw system: Include both objects and coordinates.
  2. 0 Choose consistent zero of the potential energy.
  3. Energy conservation statement:

    Ef = Ei
         Kf + Uf = Ki + Ui
    Ui - Uf = Kf - Ki
    - Δ U = Δ K
  4. Losses: Incorporate if needed.

    Ef = Ei - losses