I. Work
    A. Product of a force and a displacement.
        1. At least a component of the force must be in the direction of the displacement.
        2. W = F s cos (theta)
    B. Units
        1. See table on page 117 in text
        2. We normally use SI so will use Joules - J = Nm
    C. Be sure to define the object the work is being done on

II. Energy
    A. Definition
        1. Energy is the ability to do work.
        2. If an object has energy, it can do work on something else.
    B. Types of mechanical energy
        1. Kinetic Energy
            a. Energy an object has by virtue of its motion
            b. KE = ½ m v²
        2. Gravitational Potential Energy
            a. Energy an object has by virtue of its position (in a gravitational field)
            b. GPE = m g h
        3. Elastic Potential Energy
            a. Energy an object has by virtue of some deformation
            b. We generally look at springs, so the deformation is stretching or compressing the spring
            c. EPE = ½ k x²
                i. k is the force constant of the spring
    B. Conservation of Energy
        1. The total energy of an isolated system is constant (conserved).
            a. E_total = constant
            b. To apply in a problem, generally use E_{total 1} = E_{total 2}
                i. 1 and 2 refer to two situations of the system
        2. The change of energy of an isolated system is zero.
            a. E_total = 0
        3. Remember, these refer to the total energy. The individual types of energy can (and usually do) change.
    C. Work Energy Principle
        A. Work done on a object will produce a change in the energy of that object.
        B. W_net = E_total = KE + GPE + EPE = W_applied - W_friction

III. Power
    A. Definition
        1. Power is the rate at which work is being done (or energy is being used).
        2. P = W / t
        3. Units
            a. SI - Watt - W = J/s
            b. British - (ft lb)/s
            c. Horsepower - conversion from W or ft lb /s