## Chapter 5 Summary

- The Law of Conservation of Energy states that energy can change form but can never be created or destroyed.
- Gravitational Potential Energy is the energy an object has because of its position. If an object has height above a certain reference point, it has potential energy.
- Joule – the unit for energy or work.
- Kinetic Energy – if an object is moving, it has kinetic energy.
- Work – the application of a force to an object and the movement of the object because of the force. If the energy of an object is changing, work is being done on the object.
- Power – the rate at which work is done. Also, the rate of energy transfer.

**Equations**

- Gravitational Potential Energy (PEg) = mass (kg) x g (m/s/s) x height (m)
- PE = mgh

- Kinetic Energy (KE) = 1/2 x mass (kg) x (velocity (m/s))2
- KE = 1/2mv^2
- Work (W) = Force (N) x distance (m)
- W = Fxd
- Power (P) = Work done (J) or energy transferred (J)/ time interval (s)
- P = W/t

**Units**

- Joule – most commonly used unit of Energy or Work. Other units of Energy include the Calorie, the British Thermal Unit (BTU), and the kilowatt-hour.
- Watt – most commonly used unit for Power. Other units for Power include the Kilowatt (1000 watts) and the Horsepower (1 HP = 746 Watts)