Chapter 4 – ENERGY

EnergyEnergy—The ability to cause change and the

ability to do WORK

9 Main forms of energy:

– 1. Electrical: energy due to moving electrons

– 2. Chemical: energy stored in bonds between atoms

– 3. Thermal: energy from heat

– 4. Radiant = Light: 4. Radiant = Light: energy from the sun & light energy from the sun & light

– 5. Nuclear: energy stored in the nucleus of an atom

– 6. Sound: energy of vibrating sound waves

– 7. Magnetic: energy of magnetism

– 8. *Mechanical: Energy due to position and motion • Kinetic + Potential= Mechanical

9. Elastic potential Energy: Energy that is

stored in something that

stretches or compresses,

such a rubber band or

spring.

Kinetic Energy• KE is energy of motion. • KE = 1×m×v2

• 2

– m = mass (kg)– v = velocity (m/s)

• SI Unit for Energy is Joule (J)–Joule = kgxm2/s2 (This is NOT an equation—just

another way to write the unit)

Calculating Kinetic Energy

• What is the kinetic energy of a 44 kg cheetah running at 31 m/s?

• KE = 1 m v2

• 2

• KE =

https://www.youtube.com/watch?v=AO117teuR2Q

• Bill Nye Energy:

• On the back of your paper:

• Name as many examples of energy as you can from the video.

• Name examples of energy changes in the video.

Potential Energy (PE)• PE is energy that is stored in an object. 4 types of PE:

1. Elastic PE– Energy due to a stretch (rubber band) or compression

(spring)2. Chemical PE – Energy in the bonds between atoms (foods & fuels)

3. Gravitational PE– Energy due to an elevated position– GPE = m×g×h

• m = mass (kg)• g = gravity=9.8 m/s2 (on Earth)• h = height (m)

4. Nuclear energy: Energy stored in the nucleus of an atom.

Calculating Potential Energy

• A 65 kg rock climber ascends a cliff. What is the climber’s GPE 35 m above the base of the cliff?

• GPE=

https://www.youtube.com/watch?v=AO117teuR2Q

• Bill nye energy 22 min

• Bozeman science KE PE

• https://www.youtube.com/watch?v=BSWl_Zj-CZs

Law of Conservation of EnergyL.o.C.o. Energy--• Energy can not be created or destroyed, it

just changes form.

• Rollercoaster

• mass and spring

Mechanical Energy• Energy can be converted from Potential to

Kinetic, but the total energy doesn’t change

• Total Mechanical Energy = Kinetic + Potential

• ME = KE + PE

Nuclear Energy

• There are two types of nuclear energy• Fission and Fusion • Both forms energy are stored as mass in the

atoms of certain elements. This mass can be changed into energy under the proper conditions according to Albert Einstein's famous equation:

• nuclear fission • nuclear fusion• http://www.pbslearningmedia.org/search/?

q=fission&selected_facets=• Scroll down to fusion

Fusion & Fission • Fusion atoms are "fused"

together• In fusion lighter elements

form heavier elements• Uses

– The middle of stars• Fission the 2nd form of nuclear

energy

• The exact opposite of fusion.

• In fission atoms are broken apart.

• In fission heavier elements form lighter elements.

• Uses

– Hydrogen Bomb

– Nuclear Energy Plants

Rube GoldbergUnbelievable Rube Goldberg Machine - Google Video

•