Energy Conversion&

Conservation

Kim Lachler

Updated 2015NCES: 6.P.1

Energy Conversion the change from one form of

energy to another

Energy.asf

Energy Conversion Chemical energy

We get our energy from chemical energyHow_Our_Bodies_Use_Energy.mov How_Does_Food_Supply_Energy_.mov

Remember plants get their energy from the sun; light energy

By using photosynthesis they convert light energy into sugar- stored energy – potential energy

We eat the plants or animals that eat the plants = potential energy for us

We either store this energy- in fat – potential energy or use the energy to move – kinetic energy

Energy Conversion Calorie – how we measure the potential

energy in food calorie = 4.2 Kilojoules

Energy Conversion

A piece of buttered toast contains about 315 kilojoules of energy Jog for 6 minutes Bicycle for 10 minutes Walk briskly for 15 minutes Sleep for 1 ½ hours

Energy Conversion Machines can convert energy to make it into

forms useful for us. Alarm clock – electrical energy light

and sound energy Battery – chemical energy electrical

energy Light bulb – electrical energy light and

thermal energy

Energy Conservation

Any time energy is converted from one form to another, thermal energy is given off.

Energy Conservation Remember things move from potential

energy to kinetic energy and back again. As this happens some of the energy is

converted to thermal energy, so the potential energy becomes less and less.

Energy Conservation Energy is converted to thermal energy

by friction

Friction – a force that opposes motion between two surfaces that are in contact

Energy_Efficiency_and_Friction.movhttp://phet.colorado.edu/en/simulation/friction

Law of conservation of energy

energy can not be created or destroyed but can be changed from one form to another

An_Introduction_to_Energy_and_Work.mov

Law of conservation of energy

Closed system Where you can measure all the

different energies from start to finish of an action.

The original potential energy = all the final energies mechanical energy ( potential +

kinetic) sound energy thermal energy

Perpetual MotionPerpetual motion – a machine that would run

forever without any additional energy

Is this possible? No, because of friction.

Energy Efficient comparison of the amount of energy

before a conversion with the amount of useful energy after a conversion.

Some machines are not energy efficient – transferring most of the energy to a form you don’t want.

Energy Efficient

Car engine convert only 25% of the gasoline to kinetic energy, the rest is converted to thermal energy as a result of friction.

Energy Efficient To help keep machines efficient

oil aerodynamic

Bibliography Holt,Rinehart and Winsteon, North Carolina Holt Science & Technology, Holt,Rinehart and

Winsteon, New York, 2005 Discovery Education, http://discoveryeducation.com, accessed 12/28/2010 What is a pendulum anyway?, http://www.calacademy.org/products/pendulum/page1.htm,

accessed 12/28/2010