Transcript ENERGY
ENERGY THE DRIVING FORCE What is Energy? • The ability to do work • The ability to cause change • Force is a push or pull • Measured in Joules, Joules = kg●(m/s)2 • Formula: E = KE + PE E = .5mv2 + magravh (KE = .5 x mv2) (PE = magravh) Energy is Conserved (in a closed system) • https://www.youtube.com/watch?v=p3msL1P8bw Different Forms of Energy • 6 different types: • Mechanical • Thermal Energy • Chemical Energy • Electrical Energy • Electromagnetic Energy • Nuclear Energy Forms of Energy • Mechanical Energy • Describes energy stored and released according to function or force Forms of Energy • Thermal Energy • Heat in all its forms and flows Forms of Energy • Chemical Energy • Stored and released in the bonds between atoms Forms of Energy • Electric Energy • Energy that is caused by moving electric charges • Since the electric charges are moving, this is a form of kinetic energy. Forms of Energy • Electromagnetic Energy • Waves of mostly invisible energy • Includes light, radio waves, X-rays Forms of Energy • Nuclear Energy • Stored and released from the nucleus of an atom Two descriptions of Energy • Potential Energy - Energy stored by position or condition • Kinetic Energy - Released energy or energy of motion Potential Energy • The easiest quantified PE is Gravitational PE • This is the PE stored in an object by its height above another reference point • PEGrav = m agrav h Joules = kg●(m/s)2 Remember, agrav = 9.8 m/s2 Potential Energy, revisited… • Another form is Elastic PE • This is the PE stored in an object by its being disturbed from is natural state, • and how much it wants to return to that natural state • Good examples: • Springs, swings, pendulums, rubber bands Potential Energy, revisited… • Another form is Chemical PE • This is the PE stored in an object by the chemical bonds between its atoms and molecules • The energy is released when the chemicals react and form new bonds • Good examples: • Burning a log, firecrackers, Kinetic Energy • This is the KE released by an object by its motion • KE = ½ m v2 • Joules = kg●(m/s)2 Potential or Kinetic? • On the next few slides, tell whether the energy is potential or kinetic… A bowling ball rolling down the lane 1. Potential 2. Kinetic A sandwich 1. Potential 2. Kinetic A ball being thrown through the air in a projectile path 1. Potential 2. Kinetic A gallon of gasoline 1. Potential 2. Kinetic A lawnmower burning a gallon of gasoline 1. Potential 2. Kinetic Law of Conservation of Energy • Energy can not be created or destroyed in normal reactions • Energy can be changed from one form to another • The total amount of energy must be the same before and after a change in energy Mechanical Energy in a Pendulum Which of these describes Energy? 0% 0% 0% 0% 1. 2. 3. 4. Ability to do work Ability to cause change Ability to increase energy Ability to decrease work At which point is PE at maximum? 0% 0% 0% 0% 1. 2. 3. 4. A B C D Joules is not the unit for which of these? 0% 0% 0% 0% 1. 2. 3. 4. Potential Energy Kinetic Energy Work Force At which point is KE at maximum? 0% 0% 0% 0% 1. 2. 3. 4. A B C D