* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter 9
Dark energy wikipedia , lookup
Open energy system models wikipedia , lookup
William Flynn Martin wikipedia , lookup
Energy storage wikipedia , lookup
100% renewable energy wikipedia , lookup
Energy subsidies wikipedia , lookup
Low-Income Home Energy Assistance Program wikipedia , lookup
Potential energy wikipedia , lookup
Zero-energy building wikipedia , lookup
Public schemes for energy efficient refurbishment wikipedia , lookup
Low-carbon economy wikipedia , lookup
World energy consumption wikipedia , lookup
Energy Charter Treaty wikipedia , lookup
Alternative energy wikipedia , lookup
Energy policy of Australia wikipedia , lookup
International Energy Agency wikipedia , lookup
Regenerative brake wikipedia , lookup
Energy harvesting wikipedia , lookup
Life-cycle greenhouse-gas emissions of energy sources wikipedia , lookup
Energy policy of the United Kingdom wikipedia , lookup
Energy returned on energy invested wikipedia , lookup
Distributed generation wikipedia , lookup
Energy policy of Finland wikipedia , lookup
Internal energy wikipedia , lookup
Energy efficiency in transport wikipedia , lookup
Kinetic energy wikipedia , lookup
Negawatt power wikipedia , lookup
Energy in the United Kingdom wikipedia , lookup
Energy policy of the European Union wikipedia , lookup
United States energy law wikipedia , lookup
Energy efficiency in British housing wikipedia , lookup
Conservation of energy wikipedia , lookup
Energy applications of nanotechnology wikipedia , lookup
Energy Independence and Security Act of 2007 wikipedia , lookup
Chapter 9 Notes Energy and Energy Resources Energy is the ability to do work. Work is a transfer of energy, and like work, energy is measured in Joules (J). Forms of energy: Kinetic energy is the energy of motion. Kinetic Energy (KE) depends on mass (m) and speed (v). -1- Kinetic Energy = mass x velocity2 2 KE = mv2 2 example#1 What is the kinetic energy of a car that has a mass of 1200 kg and is moving at a speed of 20 m/s ? KE = mv2 2 KE = 1200 kg * (20 m/s)2 2 KE = 1200 kg * 400 m2/s2 2 -2- KE = 480,000 kg*m2/s2 2 KE = 240,000 kg m2/s2 or 240,000 J Practice problems: #2 What is the kinetic energy of a car that has a mass of 2400 kg and is moving at 20 m/s? KE = mv2 2 KE = 2400 kg * (20 m/s)2 2 -3- KE = 2400 kg * 400 m2/s2 2 KE = 960,000 kg*m2/s2 2 KE = 480,000 kg m2/s2 or 480 000 J How does the kinetic energy compare to the example problem above? #3 What is the kinetic energy of a car that has a mass of -4- 1200 kg and is moving at a speed of 40 m/s ? KE = mv2 2 KE = 1200 kg * (40 m/s)2 2 KE = 1200 kg * 1600 m2/s2 2 KE = 1,920,000 kg*m2/s2 2 2 KE = 960,000 kg m /s 2 or 960,000 J -5- What is the kinetic energy of a 4,000 kg elephant that is running at 2 m/s? At 4 m/s? How do the two kinetic energies compare to one another? QUADRUPLES ! #3 What is the kinetic energy of a 2,000 kg bus that is moving at 30 m/s? Potential energy -6- is energy of position or condition. It is stored energy held in readiness to do work. Gravitational, chemical, and Elastic potential energy Elastic PE is when an object is stretched or compressed. examples rubber band, ball, spring Gravitational potential energy depends on the -7- height of an object. It is measured in Joules. GPE = weight * height example: A book is placed on a shelf 2.5 meters off the floor. It has a weight of 0.65 N, what is the potential energy? GPE = weight * height GPE = 0.65 N * 2.5 m GPE = 1.625 N * m (or 1.625 J) **If you don’t know weight, but know mass of object use: -8- GPE = mass * acceleration * height of gravity GPE = M * 9.8 m/s2 * H example: A glass with a mass of 0.5 kg is on the edge of a table 1 m off the floor. What is the potential energy? GPE = M * 9.8 m/s2 * H 2 GPE = .5 kg * 9.8 m/s * 1m GPE = 4.9 kg* m/s2 *m GPE = 4.9 N*m (or 4.9 J) Other forms of energy: -9- Mechanical Energy is the total energy of motion and position of an object. It could be pushing, pulling, or throwing. examples: moving bike, running, jumping frog, sound thermal (energy of particles) chemical energy is stored in chemical bonds of the foods we eat, in a match, batteries, fossil fuels (coal, petroleum, natural gas) - 10 - electrical energy is energy from moving electrons electromagnetic energy is radiant or light energy. visible light, microwaves, ultraviolet and infrared radiation, x-rays, radio waves nuclear energy is stored in the nucleus of an atom. Released when nucleus splits (fission) like in reactors, or when nuclei join (fusion) like in stars. - 11 - The Law of Conservation of Energy When one form of energy is converted to another, no energy is destroyed in the process. **Energy can be transformed from one type to another. ***In any conversion, some of the energy is lost to the environment as heat. - 12 -