Download Chapter 9 Study Guide – Energy and Energy Resources

Chapter 9 Study Guide - Energy and Energy Resources
Section 1 - What is Energy?
Energy – the ability to do work
1. Work like energy is expressed in Joules.
Kinetic energy – the energy of an object that is due to the object’s motion
mv²
Kinetic energy = ------2
mass × velocity²
--------------------2
Speed has a greater effect on kinetic energy than mass because it is squared.
Potential energy – the energy that an object has because of the position, shape, or condition of the object
(remember, an object accelerates as it falls due to gravity, so the higher an object is lifted above the ground, the
greater the potential energy)
Gravitational potential energy – when you lift an object, you do work on it. You transfer energy to the object.
1. Gravitational potential energy = weight × height
Mechanical energy – the amount of work an object can do because of the object’s kinetic and potential energies
1. Mechanical energy = potential energy + kinetic energy
Thermal energy – the kinetic energy due to random motion of the particles that make up an object
1. Temperature is a measure of thermal energy
Chemical energy – a form of potential energy that depends on the position and arrangement of the atoms in a compound
Electrical energy – the energy of moving electrons
Sound energy – vibrating objects transmits energy through the air around it
Light energy – energy produced by the vibrations of electrically charged particles
Nuclear energy – energy that comes from changes in the nucleus of an atom
1. fusion – when nuclei join together
2. fission – when a nucleus splits
Section 2 - Energy Conversions
Energy conversion – a change from one form of energy to another
Elastic potential energy – storing potential energy in a material that stretches and can return to its original shape
1. examples are bow and arrow, crossbow, toy airplane, pulling a rubber band
Chemical energy of food is converted into kinetic energy when you are active
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
Friction – a force that opposes motion between two surfaces that are touching
1. Not all potential energy is converted into kinetic energy; much is lost due to friction
Closed system – a group of objects that transfer energy only to each other
Law of conservation of energy – states that energy cannot be created or destroyed but can be changed from one form to
another
Any time one form of energy is converted into another form, some of the original energy always gets converted into
thermal energy
Perpetual motion – a machine that would run forever without any additional energy.
1. This is impossible since some energy is always lost as thermal energy
Energy efficient – a comparison of the amount of useful energy before a conversion with the amount of useful energy
after a conversion
1. energy conversions that are efficient waste less energy
Section 4 - Energy Resources
Nonrenewable resources – a resource that forms at a rate that is much slower than the rate at which it is consumed (fossil
fuels, nuclear energy)
Fossil fuels – a nonrenewable energy resource formed from the remains of organisms that lived long ago
1. coal, natural gas and petroleum (used to make gasoline, kerosene, wax and plastics)
Electrical generators – convert the chemical energy in fossil fuels into electrical energy
1. water is pumped into a boiler
2. coal, oil or natural gas is burned in a combustion chamber
3. thermal energy is used to boil water and turn it into steam
4. thermal energy is converted to kinetic energy as the steam travels through pipes and pushes against blades of a
turbine
5. the turbine is attached by a shaft to a device called an electric generator (large magnet rotated within a large
coil of copper wire)
6. electricity is distributed to communities trough electrical wires
Nuclear energy – like a fossil-fuel plants, a nuclear power plant generates thermal energy that boils water to make steam.
1. nuclear energy is generated from radioactive elements, such as uranium
2. nuclear fission is used
Renewable resources – a natural resource that can be replaced at the same rate at which the resource is consumed
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 caused by the heating of Earth’s crust, the steam is used to turn turbines which turns
an electric generator
Biomass – organic matter such as plants, wood and waste that can be burned to release thermal energy
* Table 1 on pg. 262 has the Advantages and Disadvantages for all energy resources in this chapter