Transcript ENERGY
ENERGY Above and beyond PE & KE THE LAW: • CONSERVATION OF ENERGY • ∑ E1 =∑E2 • Energy cannot be created or destroyed; it only changes form • Energy in = energy out • Heat, light and sound are common forms of energy transfer Many types of Energy • • • • • • • Mechanical (PE & KE) Gravitational Kinetic Chemical Nuclear Electromagnetic Thermal Mechanical Energy • A object that is able to do work has mechanical energy • Examples: Cars, trains, tractors, hammers, etc Kinetic Energy (KE) • • • • The energy of motion KE=1/2mv2 Expressed as Joules (J) Example: Book falling from shelf Potential Energy (PE) • Stored energy • “The energy of position in a force field” • PE=mgh • Example: Book on a shelf • aka: gravitational energy Thermal Energy • When the amount of heat added to a system and something happens to the system, Thermal Energy is to blame • Expressed as ΔQ • Example: Heat added to water activates the water molecules, increasing the KE of the system Chemical Energy • When certain chemicals combine, energy is released • Most important source of energy right now • Example: Combustion of glucose (sugar) in our bodies • C6H12O6 +6O2 + 690 kcal/mole 6CO2 + 6H2O Electromagnetic Energy • Waves transporting energy from one point to another • Rapid variation of electric and magnetic field • Examples: radio waves, microwaves, infrared radiation, visible light, ultraviolet, x-rays, gamma rays, etc Electrical energy • Energy due to the separation of charges • Example: electricity! Nuclear Energy • aka mass energy • E= mc2 • Einstein first observed that anything with mass has energy • Unstable isotopes can be fused or split thus liberating the energy within • Examples: Fission & fusion Nuclear Energy (cont’d) • An incredibly small amount of mass has an incredibly large amount of energy • Energy=mass x speed of light squared • Speed of light = 3 x 108 m/s • 50 grams of mass has potential to level an entire city Elastic/Spring PE • http://www.sciencejoywagon.co m/physicszone/lessonch/05work/ spring/speng.htm PROBLEMS: • http://127.0.0.1:26300/Principles _of_Physics/07_Work,%20Energy %20and%20Power/06/sp.html • http://127.0.0.1:26300/Principles _of_Physics/07_Work,%20Energy %20and%20Power/07/sp.html • http://127.0.0.1:26300/Principles _of_Physics/07_Work,%20Energy %20and%20Power/09/sp.html