1. Sec. 2 & 3 Energy Transformations & Conservation
Ch. 9 Energy
Sec. 2 & 3
Energy Transformations & Conservation

2. REMINDER…
Energy can exist in different forms & can be converted from one form to another

3. NEEDED for EVERYTHING we do!
Energy Conversions
energy conversions – a change from one form of energy to another
NEEDED for EVERYTHING we do!

4. Examples of Energy Conversions
sunlight warms up a sidewalk…
radiant energy  thermal energy
a plant uses sunlight to make food…
radiant energy  chemical energy
a ball rolls off a shelf…
potential energy  kinetic energy

5. Examples of Energy Conversions
a baby crawls across the floor…
chemical energy  kinetic energy
a boy pedals a bike…
chemical energy  kinetic energy  kinetic energy
a puppy runs down a hill…
potential energy  kinetic energy

6. Energy Conversions
many machines transform energy from one form to another
ex. a car engine transforms
chemical energy [fuel] into kinetic
energy & thermal energy
ex. a radio converts electrical energy
into kinetic energy
(vibrations of the speaker)

7. Law of Conservation of Energy
law of conservation of energy - energy is neither created nor destroyed, but rather is transferred or converted from one form to another
ex. when a ball is first tossed in the air, most of the energy is kinetic - as it rises & slows it loses kinetic energy but gains potential energy thus, the total amount of energy remains constant

8. Storage & Loss of Energy
in EVERY energy transformation, SOME thermal energy is released
energy can be stored such as in a battery (electrical energy) & in food (chemical energy)
HOWEVER, thermal energy is difficult to store b/c it easily leaves an object