Chapter 12: Energy and Energy Resources Carin Miranda

What is Energy? Energy is the ability to do work.Energy is the ability to do work. Work and energy are both expressed in joules (J).Work and energy are both expressed in joules (J).

Kinetic Energy Kinetic energy is the energy of motion.Kinetic energy is the energy of motion. All moving objects have kinetic energy.All moving objects have kinetic energy. Kinetic energy= mass times speed squared divided by 2.Kinetic energy= mass times speed squared divided by 2. The faster something is moving, the more kinetic energy it has.The faster something is moving, the more kinetic energy it has. The more massive the object the more kinetic energy it has.The more massive the object the more kinetic energy it has.

Potential Energy Potential energy is energy based on shape or position.Potential energy is energy based on shape or position. Gravitational potential energy is based on height and weight.Gravitational potential energy is based on height and weight. The higher an object the more potential energy.The higher an object the more potential energy. The more massive an object the greater the potential energy.The more massive an object the greater the potential energy.

Mechanical Energy Mechanical energy is the total energy of motion and position.Mechanical energy is the total energy of motion and position. In other words it is kinetic plus potential.In other words it is kinetic plus potential. As potential goes up kinetic goes down and vice versa.As potential goes up kinetic goes down and vice versa.

Forms of energy Thermal (Heat)Thermal (Heat) ChemicalChemical ElectricalElectrical SoundSound LightLight NuclearNuclear

Thermal Higher temperature objects have more thermal energy and more kinetic energy.Higher temperature objects have more thermal energy and more kinetic energy. The particles in steam move faster than the particles in ice.The particles in steam move faster than the particles in ice. The more particles the more thermal energy.The more particles the more thermal energy. A bathtub full of 75 degree water would have more thermal energy than a cup full of 75 degree water.A bathtub full of 75 degree water would have more thermal energy than a cup full of 75 degree water.

Chemical Energy When particles are broken down and cannot return to their original form they have chemical energy.When particles are broken down and cannot return to their original form they have chemical energy. Examples: Food, Charcoal, gasoline, firewood.Examples: Food, Charcoal, gasoline, firewood.

Electrical Energy Moving electrons.Moving electrons. Any electrical appliances or anything using electricity.Any electrical appliances or anything using electricity. Huge magnets are rotated to produce the electricity you use at home.Huge magnets are rotated to produce the electricity you use at home.

Sound Energy Caused by an objects vibrations.Caused by an objects vibrations. It is a form of potential and kinetic energy.It is a form of potential and kinetic energy.

Light Energy Vibrations of electrically charged particles.Vibrations of electrically charged particles. Not all light energy is seen.Not all light energy is seen. Microwaves use light energy.Microwaves use light energy.

Nuclear Energy Two or more nuclei join together (nuclear fusion). Example: SunTwo or more nuclei join together (nuclear fusion). Example: Sun Nucleus of an atom splits apart (nuclear fission). Example: Uranium atoms split apart to produce electricity.Nucleus of an atom splits apart (nuclear fission). Example: Uranium atoms split apart to produce electricity.

Energy Conversions Any change from one form of energy to another.Any change from one form of energy to another.

Kinetic to Potential Remember we said as potential energy goes up kinetic goes down and vice versa.Remember we said as potential energy goes up kinetic goes down and vice versa. Examples: Person on a trampoline, pendulum, and wind up toys.Examples: Person on a trampoline, pendulum, and wind up toys.

Chemical Energy Conversions Chemical energy in food is converted into kinetic energy when you move.Chemical energy in food is converted into kinetic energy when you move. It is stored as potential energy when you aren’t moving.It is stored as potential energy when you aren’t moving. Where did that chemical energy come from in food?Where did that chemical energy come from in food? The sun gives plants light energy and they convert it into chemical energy.The sun gives plants light energy and they convert it into chemical energy. Batteries are another example of chemical energy.Batteries are another example of chemical energy.

Electrical Energy Conversions Lots of examples:Lots of examples: Alarm clock: electrical to light and sound.Alarm clock: electrical to light and sound. Battery: chemical to electricalBattery: chemical to electrical Light bulb: electrical to light, thermal, and sometimes sound.Light bulb: electrical to light, thermal, and sometimes sound. Blender: electrical to kinetic and soundBlender: electrical to kinetic and sound

Energy and Machines Machines make work easier by changing the size and/or direction of the force required to do the work.Machines make work easier by changing the size and/or direction of the force required to do the work.

Why Conversions are Important Make energy useful.Make energy useful. Make conversions more efficient.Make conversions more efficient.

Conservation of Energy Friction is a force that opposes motion between two surfaces that are touching.Friction is a force that opposes motion between two surfaces that are touching. When energy is used to overcome friction some energy is converted into thermal energy.When energy is used to overcome friction some energy is converted into thermal energy. On a roller coaster potential energy is greatest at the top of the biggest hill and kinetic energy is greatest at the bottom of the biggest hill.On a roller coaster potential energy is greatest at the top of the biggest hill and kinetic energy is greatest at the bottom of the biggest hill.

Law of Conservation of Energy Energy can be neither created nor destroyed.Energy can be neither created nor destroyed. It can change from one form to another.It can change from one form to another. Every time an energy conversion takes place some energy is always converted into thermal energy.Every time an energy conversion takes place some energy is always converted into thermal energy.

Energy Resources A natural resource that can be converted by humans into another form of energy to do useful work.A natural resource that can be converted by humans into another form of energy to do useful work. Can be nonrenewable or renewable.Can be nonrenewable or renewable.

Nonrenewable Cannot be replaced easily.Cannot be replaced easily. Fossil Fuels: Formed from the buried remains of plants and animals that lived millions of years ago.Fossil Fuels: Formed from the buried remains of plants and animals that lived millions of years ago. Coal, petroleum, and natural gas.Coal, petroleum, and natural gas. Electrical energy from fossil fuels.Electrical energy from fossil fuels. Nuclear Energy (Uranium pellets).Nuclear Energy (Uranium pellets).

Renewable Can be replaced over a relatively short period of time.Can be replaced over a relatively short period of time. Solar Energy (SUN).Solar Energy (SUN). Energy from water (Hydroelectric).Energy from water (Hydroelectric). Wind Energy.Wind Energy. Geothermal (Hot water in the ground).Geothermal (Hot water in the ground). Biomass (garbage).Biomass (garbage).

Advantages and Disadvantages of Nuclear Energy Advantages: very concentrated form of energy and nuclear power plants don’t produce smog (CO2).Advantages: very concentrated form of energy and nuclear power plants don’t produce smog (CO2). Disadvantages: Produces radioactive waste and it is nonrenewable.Disadvantages: Produces radioactive waste and it is nonrenewable.