Energy Conversions and Conservation Week of December 3rd

Journal Entry 12/3/12 What does a plant, a stove, and a pendulum have in common?

Energy Conversion Energy Conversion is a change from one form of energy to another. Any form of energy can change into any other form of energy.

Kinetic and Potential Kinetic and Potential energy conversions. Skater on a ramp. Pendulum Activity

Elastic Potential Energy When something is stretched, like a rubber band, it stores its energy as elastic potential energy. When the rubber band is released the potential energy is converted to kinetic energy as the rubber band returns to its original shape.

Conversions involving Chemical Energy Chemical energy of food is converted into kinetic energy when you are active. Chemical energy is converted into thermal energy to maintain body temperature.

Conversions involving Electrical Energy Table 1: Some Conversions of Electrical Energy Alarm clock electrical energy to light energy and sound energy Battery chemical energy to electrical energy Light bulb electrical energy to light energy and thermal energy Blender electrical energy to kinetic energy and sound energy

Energy and Machines A machine can make work easier by changing the size or direction (or both) of the force needed to do the work.

Energy and Machines cont. Machines help you use energy by converting it into the form that you need. Example: radiometer

Journal Entry 12/5/12 Where does the energy that makes a roller coaster car move come from?

Energy Conversions in a Roller Coaster Not all of the cars’ potential energy is converted into kinetic energy as the cars go down the first hill. In addition, not all of the cars’ kinetic energy is converted into potential energy as the cars go up the second hill. Some of it is changed into thermal energy because of friction.

Law of Conservation of Energy The law that states that energy cannot be created or destroyed but can be changed from one form to another.

Conservation of Energy cont. All of the different forms of energy in a system always add up to the same total amount of energy.

Conversions and Thermal Energy Any time one form of energy is converted into another form, some of the original energy always gets converted into thermal energy.

Energy Efficiency Energy efficiency is a comparison of the amount of energy before a conversion with the amount of useful energy after a conversion. The difference is often due to thermal energy because of friction.