ENERGY – is the ability to do work or cause change Work is a transfer of energy. When energy is transferred, the object upon which work is done gains energy. POWER = energy transferred (work) time

KINETIC ENERGY - is energy an object has due to motion. -it depends on MASS and VELOCITY - kinetic energy INCREASES when either mass or velocity INCREASES

KINETIC ENERGY= ½ ½ 1/2 x mass x velocity 2 *changing the velocity has a greater effect than changing the mass* COMPARE the following: 1) a 20kg object moving at 10 km/hr: KE = 1/2(20)(10 2 ) = (10)(100) = 1,000 2) a 40 kg object moving at 10 km/hr KE = 1/2(40)(10 2 ) = (20)(100) = 2,000 3) a 20 kg object moving at 20 km/hr KE = 1/2(20)(20 2 ) = (10)(400) = 4,000

POTENTIAL ENERGY - is stored energy as a result of position or shape. -gravitational PE is related to the object’s HEIGHT and WEIGHT - gravitational potential energy INCREASES when either weight or height INCREASES

Gravitational Potential energy = weight x height Example: height or the weight of a skier on a jump will effect the GPE

ELASTIC POTENTIAL ENERGY - is potential energy associated with objects that can be stretched or compressed Examples: rubber band, bow and arrow, sponge

Potential and Kinetic energy work in opposing pairs! As one increases, the other decreases!

Forms of Energy 1) Mechanical Energy – this is energy associated with position and motion of an object. An object with mechanical energy can do work on another object! ME = WORK ME = potential energy + kinetic energy 2) Thermal energy – is the total potential and kinetic energy of the particles in an object For example: hot lava has high thermal energy KE = thermal energy

3) Electrical Energy – is the energy of electric charges (getting a shock) For example: lightening, battery energy, outlets 4) Chemical Energy – is the potential energy stored in chemical bonds that hold compounds together. Stored in food, cells etc.) For Example: when your body breaks food down, it breaks the bonds holding the atoms together, this RELEASES ENERGY that our bodies can now use.

5) Nuclear Energy – is the energy stored in the nucleus of an atom. It is released during a nuclear reaction: fission – the nucleus splits and releases energy fusion – nuclei fuse (join) together and release energy. This occurs on the SUN. 6) Electromagnetic Energy – is energy that travels in waves. These have electrical and magnetic properties. For Example: sunlight, radio waves, UV rays, X- rays

ENERGY TRANSFORMATIONS & CONSERVATION Most forms of energy can be transformed into other forms. An ENERGY TRANSFORMATION -is a change from one form of energy to another.

Single transformation: one form another form Examples: 1) A toaster turns electrical energy to thermal energy 2) Cell phone turns electrical to electromagnetic 3) Your body turns chemical energy to mechanical energy

Multiple transformations: one form another form another form For Example: 1) A match turns mechanical to thermal to chemical back to thermal to electromagnetic! 2) A car turns electrical (spark) to thermal to chemical to thermal to mechanical and back to electrical!

Transformations between KINETIC & POTENTIAL This is the most common energy transformation! As one increases, the other decreases!!

Energy transformation in a pole vault: kinetic elastic potential graviational potential kinetic (falling)

CONSERVATION of ENERGY says: “Energy CANNOT be created OR destroyed! It can only be converted into other forms.” The TOTAL amount of energy is the SAME BEFORE AND AFTER any transformation!! 1) Friction causes some kinetic energy to become thermal energy (heat). Think about rubbing your hands together! 2) Some matter can be transformed into energy, so in reality: “Matter and energy together are always conserved!”