ENERGY. The Nature of Energy What is Energy? Energy is the ability to cause change Energy can change the temperature, shape, speed or direction of an.

ENERGY

The Nature of Energy• What is Energy?

• Energy is the ability to cause change• Energy can change the temperature, shape, speed or direction of an object

• Energy can change the shape of modeling clay or the temperature of a cup of water

Figure 1- You can use the energy of your muscles to change the speed of a bicycle by pedaling faster, slower, or putting on the brakes

Explain How these Objects cause Change.

Energy of Motion• Kinetic energy is the energy

an object has due to its motion (movement)• If an object is not moving, it

does not have kinetic energy• Kinetic energy increases as an

object moves faster• Kinetic energy increases as the

mass of the object increases

Figure 2- The bowling ball has kinetic energy because it is rolling down the alley

Energy of Position• Potential Energy is the energy stored in an object because of its position• Potential energy of an object is greater the higher above the ground it is

• Potential energy is also greater, the more mass an object has

Figure 3- Which object has more Potential Energy?

Forms of Energy• Thermal Energy

• Energy of moving particles in an object• All objects have thermal energy

that increases as its temperature increases

• A cup of hot chocolate has more thermal energy than a cup of cold water

• Thermal energy released by chemical reactions come from another form of energy called Chemical Energy

• Chemical Energy• The energy stored in chemical

bonds- when chemicals are broken apart and new chemicals are formed, some of this energy is released

Thermal Energy • Temperature

• Measure of the average kinetic energy of the moving particles in an object (measure of thermal energy in an object)• The greater the average kinetic

energy is, the higher an object’s temperature is (the particles are moving faster in an object with higher temperature)• There are different scales used

to measure temperature where the units are different (example: Fahrenheit, Kelvin and Celsius)• Water boils at 212F or 100C

and freezes at 32F or 0C• 0 K is the ABSOLUTE lowest

temperature an object can have

• Heat• Transfer of thermal energy from

one object to another because of difference in temperature is called HEAT.• Heat flows from hot to cold (HOT

COLD)• Thermal energy is transferred in

three ways: radiation, convection or conduction

Forms of Energy (continued)…• Light Energy

• Objects absorb energy from light and this energy is transformed into thermal energy

• The energy carried by light is called radiant energy

• Electrical Energy• Energy that is carried by an

electric current where electrons move within an object

• Solar Energy• Nuclear Energy

• Energy contained by atomic nuclei that can be transformed into other forms of energy

Brain Pop Videos• Forms of Energy• Kinetic Energy• Potential Energy• Current Electricity• Wind Energy• Solar Energy• Nuclear Energy• Thermal Energy

Forms of Energy

Forms of Energy

MechanicalThermalChemical

ElectricalElectromagneticNuclear

Energy can be transferred, or

converted, from one form to

another!

Mechanical Energy

Energy associated with the motion of an object.

ChewingSoundFrog Dancing

Thermal Energy

Total energy of the particles in a substance or material.

All objects give off thermal energy

Ice cream melting gains thermal energy

Chemical Energy

Potential energy stored in chemical bonds.

FoodFire CrackerStomach Battery

Electrical Energy

Moving electrical charges that produce electricity and energy.

Static ShockLighteningComputers/

TVs/RadiosLights

Electromagnetic Energy

Energy that travels in waves

Visible lightUV RaysMicrowaves

Nuclear Power

Energy stored in the nucleus of an atom from fission or fusion

SunStarsNuclear

Power Plant

Energy Transformations• Chemical, thermal, radiant,

and electrical are some forms that energy can have.

• Around us, energy is continually transforming

• E.g: The ability to transform energy allows a biker to climb a hill

• Energy transformations can occur when people exercise, when a car runs, when living things grow and even when stars explode- they all produce thermal energy

• Energy is never created or destroyed• It is merely transformed• Energy cannot be made but

must come from the natural world

• Can energy ever be lost? Why or why not?

• Read Green Book pages 723-727

Changing Forms of Energy The Law of Conservation of Energy

This is the last slide for 6th graders.7th Graders continue to the last slide…

Energy Resources

Non-Renewable• Fossil fuels

• Coal, oil, gases• Nuclear Energy

• non renewable waste products: Uranium

More Alternative Resources• Energy from the Oceans

• Tidal Energy (inexhaustible, non-polluting but limited)

• Wind• Inexhaustible

• Windmills convert kinetic energy of the wind into electrical energy

Energy Resources

Renewable• Hydroelectricity

• Rivers flowing, rain, snow fall provide energy to hydroelectric plants

Alternative/Renewable Resources• Solar Energy

• Inexhaustible resource where radiant energy is collected and transformed into electrical energy using a photovoltaic

• Geothermal Energy• Heat generated inside Earth that is

produced when unstable radioactive atoms inside Earth decay which converts nuclear energy into thermal energy

• See Brainpop video on ENERGY SOURCES

Properties and Changes of Matter• Physical Properties

• A physical property is a characteristic that you can observe without changing or trying to change the COMPOSITION of the substance

• How something looks, smells, sounds or tastes are all examples of physical properties

• To describe a sample of matter, you need to identify its state: solid liquid or gas…

• Physical properties of substances can include: State, density, melting point, boiling point and solubility.

• Physical Change• Any change in size, state

(condensation, evaporation sublimation, deposition, freezing, melting), shape or form of a substance

• Chemical Properties• A chemical property is a

characteristic that cannot be observed without alternating the substance (ability of a substance to undergo a change that alters its identity)

• The ability to burn is a chemical property because the composition of the substance changes permanently after being burned

• Chemical Change• Change where substances are

changed into different substances• Examples would be oxidation,

rust, fireworks and leaves changing color

Physical Properties—describe matter•Melting and boiling point are physical properties (the temperature at which a substance melts or boils)

•State of matter is also a physical property (solid, liquid, gas)

•Density is a physical property • Density is a measure of how closely packed an object’s atoms are

• Unit of density: g/cm3 (mass/volume)

Solid Liquid Gas

Has a definite shape

Takes on shape of container

Does not have definite shape

Particles are close together and move slowly

Particles are farther apart and faster moving

Particles are farthest apart and move rapidly

Has volume Has volume Expands to take up whatever space is available

Ice changes to water—water changes to ice, frozen water is still water

Water changes to steam, a gas, when it is heated to its boiling point,water vapor condenses to form a liquid

Other Physical Changes• Breaking• Crushing• Cutting• Bending• Melting• Freezing• Boiling

• Can happen naturally• People can cause changes

• Water evaporating (boiling water)

• Recycling paper• Recycling metal

Chemical Properties and Changes

• Chemical changes change the chemical nature and properties of substances to form new substances

• A match burns• Two substances mix together turn a color different from either of them

• Toasting marshmallows• Melt it—physical change• Burn it—chemical change

Law of Conservation of Mass• During a chemical change, the form or the composition of the matter changes. The particles within the matter rearrange to form new substances, but they are not destroyed and new particles are not created. The number and type of particles remain the same. As a result, the total mass of the matter is the same before and after a physical or chemical change.