Energy

• Energy – is defined as the ability to do work; the ability to cause change; all energy can be transferred

• Two main types of Energy: – Kinetic Energy: Is the energy an object has due to its

motion– Potential Energy: Is energy stored in an object due to its

position (the higher you are…)– See Handout

• Mechanical Energy– The sum of the kinetic and potential energy of an object is

the mechanical energy of the object.

Thermal Energy

• Is the sum of the kinetic and potential energy of a the particles in an object due to their motion; transfer of heat; energy of hot objects– 3 Ways: Conduction, Convection, RadiationIt all has to do with HEAT & Temperature- Temperature: is the measure of the average

kinetic energy of the particles in a materialConnection: The temperature of a material increase

as the thermal energy of the material increases!

Energies

Chemical Energy• When you are eating you are providing

your body with energy…but how does your body convert a burger into body fuel (energy)

• The chemical compounds in food contain molecules

• In these molecules there is energy• When your stomach breaks down your

burger it breaks the molecule bonds and releases energy

• Chemical energy: is the energy stored between bonds; it’s a kind of potential energy b/c it’s waiting to be released or split apart; it is released when chemical reactions occur.

Electromagnetic Energy• Is energy that travels in

waves, like the sun • Includes: Radio waves,

microwaves, light and X-rays (electromagnetic)

Energies

Electrical Energy• Is energy that is carried by

an electric current• ALL electrical appliances

convert electrical energy into other forms of energy

• It occurs when electrons are released (charge is changed….and a BOND takes energy!!!)

Nuclear Energy• This energy begins at the very

center of an atom – its NUCLEUS• Nuclear Energy is energy that is

stored in the nucleus of an atom• It is released when a change

occurs – nuclei can be joined together (like in the sun, forming fusion) or split apart (like in a nuclear power plant where uranium atoms are split apart called nuclear fission) – the energy from this is used to produce electrical energy

Measuring Energy

• In the SI system of units, energy is measured using a unit called the joule (J).

• Another unit for energy is the calorie. One calorie is the amount of energy needed to warm one gram of water by 1°C

• A different energy unit is used to measure the energy content of food. Calorie.

The LAW!

• Law of Conservation of Energy -> Energy can’t be created nor destroyed; It Flows or is Converted/Transferred– It FLOWS throughout environment between Biotic

and Abiotic factors• (Biotic – Living things; Abiotic – non living things that

interact in the environment)– HOW??? As it flows through; it transforms into different kinds of

energy» Examples:

• Photosynthesis- Light energy is transferred into chemical

Energy Flow• Energy flows through our environment as

it is converted from one form to another.• It also flows when it is transferred from

one organisms to another.

Food Chains• A food chain is a way of showing how

energyand matter can be passed or transferredfrom one organisms to another.

Energy Pyramid• Food chains and food webs have different levels of

organisms depending on one another in an ecosystem.

• As producers get eaten by consumers, energy andmatter is transferred from on organism to theother in that ecosystem. • An energy pyramid is the amount of energy available at each feeding level in an ecosystem.

Transformers!

• Energy is continually changing from one form to another. These changes from one energy form to another are called transformations.– The total amount of energy you have before it changes

will be the same as the energy you have afterwards it will just be in different forms

– Ex. When you ride a bike you are transforming chemical energy to kinetic energy. Chemical energy is also transformed into thermal energy and you feel hotter.

• Thermal energy is ALWAYS produced when energy changes

Transforming Examples

• Kinetic to Potential -> Paper Ball• Thermal Energy -> Conduction, Convection, Radiation• Thermal -> Mechanical -> Chemical -> Thermal: A Car, p289• Potential to Chemical to Kinetic -> Big Mac! Yum! • Electrical to Mechanical to thermal -> A Fan, p291• Nuclear to Thermal and more -> Stars, p292

Worn out Energy!

• The more you use or convert something, the more worn out it gets…

• When energy is changed from one form to another, it becomes less concentrated and more spread out.

• Energy that does work is Usable & is Organized• Energy that is not usable is called Waste Energy & is

Disorganized• Example: When the flashlight is used, the light and

thermal energy produced is transferred to the air surrounding the flashlight– The more we use it the less “usable “ it is…WHY?

WHY? Disorder & Entropy

• The amount of disorganized energy in the universe is always increasing

• Therefore, the more we use the energy and it spreads out, the more disorganized (waste) it becomes

• We measure this through ENTROPY– The “entropy” of a system is a measure of the

disorder, p. 291 – “Entropy always Increases”

Conserving Energy

• Nonrenewable Resources- Can NOT be replaced by natural processes in less than 100 years; Ex: Fossil Fuels (is an energy resource from buried remains of ancient plants and dead stuff – we use it to generate electricity)

• Renewable Resources – resources that can be recycled or replaced by natural processes in less than 100 years

Burning of Fossil Fuels – Electricity, Gas, Heat, etc.• Global Warming• Greenhouse Effect• What do we do? Alternative Forms of Energy!

Alternative Forms of EnergySolar Energy

• Energy that comes from the sun!

• Solar cells actively collect energy from the sun and transform it into electricity

• Is clean and inexhaustible energy

• Disadvantages:– Cloudy days– Storage – Worn out batteries

Wind Energy• Wind is air in motion• Wind energy is converted

into electricity

Alternative Forms of Energy

Hydropower• Water packs a hefty punch!• It is harnessed through Dams• Water doesn’t work alone:

– Solar energy heats water on the surface, causing it to evaporate.

– This water vapor condenses into clouds and falls back onto the surface as precipitation (rain, snow, etc.).

– The water flows through rivers back into the oceans, where it can evaporate and begin the cycle over again.

Dams & their workings

Alternate Forms of Energy

Geothermal• The word geothermal comes

from the Greek words geo (earth) and therme (heat).

• Geothermal energy is heat from within the Earth.

• We can recover this heat as steam or hot water and use it to heat buildings or generate electricity.

• Examples: Volcanoes, Hot springs, Geysers

Biomass• is organic material made from plants

and animals.• Biomass contains stored energy from

the sun. • Plants absorb the sun's energy in a

process called photosynthesis. • The chemical energy in plants gets

passed on to animals and people that eat them.

• When burned, the chemical energy in biomass is released as heat.

• Can be used as fuel, heat, biomethane, or methane gases