1. Energy Review of Chapter 4

2. Energy Energy can neither be created or destroyed Law of Conservation of Energy Law of Conservation of Energy We can only change it from one form into another We can only change it from one form into another Energy is classified in two categories (forms) Kinetic The energy of motion The energy of motionPotential Energy that is stored Energy that is stored

3. Energy Kinetic How much kinetic energy an object has depends on how much mass it has and how fast it is moving Energy is related to mass and velocity by the following equation: o Ke=1/2mv 2 The unit for Kinetic energy is the Joule. The unit for Kinetic energy is the Joule.

4. Energy Potential Potential energy can be classified into four categories Potential energy can be classified into four categories Chemical Potential Energy stored in chemical bonds Energy stored in chemical bonds Elastic Potential Energy that is stored in things that stretch, twist or compress Energy that is stored in things that stretch, twist or compress Gravitational Potential Energy Energy that is stored due to its position above the earth Energy that is stored due to its position above the earthPotential Stored energy due to position Stored energy due to position

5. Energy Chemical Potential Energy We change the energy stored in the chemical bonds of gasoline into the kinetic energy of a car in motion. We change the energy stored in the chemical bonds of gasoline into the kinetic energy of a car in motion. We change the chemical energy stored in a battery into the kinetic energy of a spinning motor that runs a personal fan. We change the chemical energy stored in a battery into the kinetic energy of a spinning motor that runs a personal fan.

6. Energy Elastic Potential Energy We store energy in a watch spring by compressing it ( winding) that changes into kinetic as the spring unwinds. We store energy in a watch spring by compressing it ( winding) that changes into kinetic as the spring unwinds.

7. Energy Gravitational Potential Energy We use gravitational potential energy in roller coaster design. We pull the cart up to the highest point so it has maximum potential energy and change that energy into motion of the cart as goes along the track. Gravitational Potential Energy is related to mass and height above the earth by the following equation: o G pe = m 9.8m/s 2 h

8. Energy Work  Energy working over a distance.  Something has to move in order for work to be done  Work is related to Force and distance by the following equation: o W = F d W is in Joules = J = Kg m 2 /s 2 W is in Joules = J = Kg m 2 /s 2 F is in Newtons = N = Kg m/s 2 F is in Newtons = N = Kg m/s 2 d is in Meters = m d is in Meters = m

9. Energy Power  Amount of work done or the amount of energy transferred over time.  Power is related to work or energy and time by the following equation: o P = w / t P is in Watts = W = j/s P is in Watts = W = j/s w is in joules = J = kg m 2 /s 2 w is in joules = J = kg m 2 /s 2 t is in seconds = s t is in seconds = s