What is Energy? .

What is Energy? The ability to do work or cause change.

What are the different forms of Energy? Energy has a number of different forms, all of which measure the ability of an object to do work on or change another object. In other words, there are different ways that an object can possess energy.

All types of energy can be transformed into other forms. Forms of Energy All types of energy can be transformed into other forms. Mechanical Potential Kinetic Chemical Nuclear Light/Radiant Thermal Sound Electrical

Energy Kinetic: The energy of an object due to it’s motion the greater the mass or speed, the greater it’s kinetic energy Potential: The energy of an object due to it’s position the greater the mass or height, the greater it’s potential energy

Example A waterfall has both kinetic and potential energy. The water at the top of the waterfall has stored potential energy. Once the water leaves the top of the waterfall, the potential energy is changed into kinetic energy.

Mechanical Energy Combined total of potential and kinetic energy of an object Chains pulling up the roller coaster, hammer hitting a nail, turning on a flashlight

Chemical Energy Energy that comes from chemical changes Stored in the connections between atoms We use food for chemical energy so we can perform Fuels produce chemical energy Fire works Batteries have stored chemical energy which changes to electrical energy when turned on

Nuclear Energy Energy stored in the nucleus of an atom (holds the atom together) Produced when an atom splits apart (Fission) Nuclear power plant Produced when 2 atoms join to form 1 atom (Fusion) The sun’s energy is produced when Hydrogen (H) atoms fuse to form Helium (He).

Electrical Energy Associated with the movement of electrons through a wire or circuit Produced by electric charges Power running the chains that pull up the roller coaster generator has a loop of wire that spins creating an electrical current Appliances use it to work

Radiant Energy Also called Light or Electromagnetic Energy Travels in waves and can move through empty space Energy carried by light and other kinds of EM waves Sunshine, Visible Light, x-rays

Light / Radiant Energy Travels in the form of electromagnetic waves, most of which we can not see. Classified by wavelength (pg 309 SS) Gamma rays have the shortest wavelength Radio waves have the longest Visible light is in the middle All the colors of the rainbow When they are all combined you see them as white light Roy G Biv (name to remember order of colors) Electromagnetic Spectrum: Full range of electromagnetic waves

Sound Energy The energy of vibrations carried by matter (air, water, solids). Sound waves canNOT travel through empty space Telephone

Thermal Energy Total Amount of Kinetic Energy contained in all particles of a substance The more particles a substance contains, the greater the thermal energy More thermal Energy does not mean a higher temperature. Ocean is massive, therefore has more thermal energy than a pot of boiling water, but is not hotter. Wood fire produces heat

Energy Transformations All types of energy can be transformed into other types. Law of Conservation of Energy: Energy can not be created or destroyed. It can only be changed into other forms of Energy.

Temperature and Heat TEMPERATURE The measure of the average kinetic energy of the particles in a substance. More kinetic energy = higher temperature HEAT The transfer of thermal energy between substances that are at different temperatures. Heat will transfer from the object with the higher temperature to the object with the lower temperature until the temperature is the same Heat makes molecules move faster and spread. Heat spreads out in all directions. Heat flows from warm water to the ice cubes, melting the ice as the water cools.

Transfer of Thermal Energy

Methods of Heat Transfer CONDUCTION CONVECTION RADIATION

Conduction Transfer of heat from a warmer substance to a cooler substance through direct contact Energy from faster moving particles is transferred to slower moving particles until both are moving at the same speed and their temperature is equalized Conductor: transfers heat very well (metal) Insulator: does not transfer heat very well (wood)

Conductors and Insulators Material through which energy can be transferred as heat Metal is an excellent conductor, wood is not. Insulator: Material that reduces or prevents the transfer of heat “Bad Conductors”. Wood

Convection Transfer of heat (thermal energy) within liquids and gases. Cold water on a hot stove As the water on the bottom heats up, it becomes less dense (particles spread out) Because the warm water is less dense than the cold water above it, the warm water rises and displaces the cold water, which sinks and warms. Heat always moves from warmer to cooler areas This movement of water is called a Convection Current: moves warm and cool molecules around until they are evenly mixed an the same temp.

Convection

Radiation Transfer of energy as electromagnetic waves Can occur in empty space Moves heat around in waves Sun releases some it’s heat energy as infrared waves Infrared Waves: low frequency light wave that is invisible to humans but felt as heat. (toasters, heaters)

Green House Effect