# Chapter 9 Study Guide

Section 1 - What is Energy?

Energy - The ability to do work

Work, like energy, is expressed in Joules

Kinetic Energy - The energy of an object that is due to the object’s motion

Potential Energy - The energy that an object has because of the position, shape, or condition of the object

Gravitational Potential Energy - When you lift an object, you do work on it. You transfer energy to the object.

Mechanical Energy - The amount of work an object can do because of the object’s kinetic and potential energies

ME = Potential Energy + Kinetic Energy

Thermal Energy - The kinetic energy due to the random motion of the particles that make up an object

Chemical Energy - This is a form of potential energy. It depends on the position and arrangement of the atoms in a compound. Forms of stored chemical energy are thermal and sound.

How does energy conversion happen?

Step 1: Starting with coal which is a chemical & potential then burn it, Thermal which is (kinetic).

Step 2: Burn water to create steam which is forced thru pipes in turbines making it spin and that’s mechanical

Step 3: Then go to the electricity

Step 4: Then turn on the light (electrical) or blow dryer (thermal, mechanical, and sound)

Nuclear Energy - Energy that comes from changes in the nucleus of an atom

Fission - This is when atoms split and give off energy

Electrical Energy - The energy of moving electrons

Sound Energy - Vibrating objects transmit energy through the air around them

Light Energy / Radiant Energy - Energy produced by the vibrations of electrically charged particles

Section 2 - Energy Conversions

Energy Conversion - A change from one form of energy to another

Examples of Energy Conversion:

The Chemical Energy of food is converted into kinetic energy when you are active. Energy is never lost. It is conserved. Energy conversions are more efficient when they use less energy. Efficiency in automobiles has been affected by the materials used to build cars and the size of cars.

Photosynthesis - Plants use light energy to make new substances that have chemical energy.

*There are several examples of conversions of electrical energy in Table 1 on pg 251*

Section 3 - Conservation Of Energy

Law of Conservation of Energy - states that energy cannot be created or destroyed (energy is never lost) but can be changed from one form to another (just changes forms).

Energy conversions that are efficient waste less energy.

Section 4 - Energy Resources

Nonrenewable Resource - This is a natural resource that cannot be reused or replaced.

Fossil Fuels - nonrenewable: coal, natural gas, and petroleum. They are used to make gasoline, kerosene, wax, and plastic.

Electrical Generators - Convert the chemical energy in fossil fuels into electrical energy.

Renewable Resource - a natural resource that can be replaced at the same rate at which the resource is consumed. ex. lithium-ion, hybrid, wind, solar, and biomass.

Solar Energy - sunlight is changed into electrical energy through solar cells

Hydroelectric Energy - falling water from a dam turns a turbine which is connected to an electric generator.

Wind Energy - The kinetic energy of the wind turns the blades of a windmill which turns an electric generator.

Geothermal Energy - Thermal energy is caused by the heating of the Earth’s crust. The steam is used to turn turbines which turn an electric generator.

Biomass - Organic matter such as plants, wood, and waste that can burn to release thermal energy.

(JOULES) (KG) (METER/SEC)

K.E. = MASS x VELOCITY^2

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2

P.E. = WEIGHT x HEIGHT

(N) (M)

• MULTIPLY MASS x 9.8 TO CONVERT MASS TO WEIGHT