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# Energy

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### Energy

1. 1. ENERGY What is energy?
2. 2. Energy <ul><li>Energy is the ability to do work to cause change </li></ul><ul><li>Energy is required for motion </li></ul>
3. 3. Kinetic energy <ul><li>Kinetic energy is the energy of matter in motion </li></ul><ul><li>Types of kinetic energy </li></ul><ul><ul><li>Chemical </li></ul></ul><ul><ul><li>Nuclear </li></ul></ul><ul><ul><li>Electromagnetic </li></ul></ul><ul><ul><li>Thermal </li></ul></ul><ul><ul><li>Mechanical </li></ul></ul>
4. 4. Kinetic Energy Kinetic Energy (KE) = ½ mass x velocity 2 KE = 1/2mv 2 Unit = JOULE (J) = 1kg/m 2 /s 2
5. 5. Energy <ul><li>Energy cannot be created or destroyed only changed or transformed </li></ul><ul><li>Hand to Ball to Hand </li></ul><ul><ul><li>Chemical to mechanical to heat to mechanical to chemical </li></ul></ul>
6. 6. Potential energy <ul><li>Potential energy is stored energy </li></ul><ul><li>An object at rest has the potential to have motion </li></ul><ul><li>Kinetic – energy of motion </li></ul><ul><li>Potential – stored energy </li></ul>
7. 7. Gravitational Potential Energy <ul><li>GPE is the energy an object can change to kinetic if it falls </li></ul><ul><li>GPE = mass x height x gravity (9.8m/s 2 ) </li></ul><ul><li>KE = ½ mv 2 </li></ul><ul><ul><li>KE = ½(70kg) x (10m/s 2 ) 2 = 3,500 J </li></ul></ul>
8. 8. Energy <ul><li>Greatest potential energy – start of slide </li></ul><ul><li>Least potential energy – end of slide </li></ul><ul><li>Greatest kinetic energy – middle of slide </li></ul><ul><li>Least kinetic energy – start & end of slide </li></ul><ul><li>Total energy remains the same it is just transferred between Kinetic and Potential </li></ul>
9. 9. Forces on a roller coaster http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/energy/ce.html http://science.howstuffworks.com/roller-coaster3.htm
10. 10. Roller coaster forces
11. 11. Energy Problems <ul><li>½ (6) x 10 2 = 300 J (3 x 100) </li></ul><ul><li>30 x 9.8 x 15 = 4410 J </li></ul><ul><li>1 x 9.8 x 2 = 19.6 J </li></ul><ul><li>½ (1) x (2.2) 2 = 2.42 J (.5 x 4.84) </li></ul><ul><li>½ (1,000) x 20 2 = 200,000 J (500x400) </li></ul><ul><li>½ (1,000) x 40 2 = 800,000 J (500x1,600) </li></ul>
12. 12. What kind of energy? <ul><li>An infrared lamp in a restaurant keeps food warm? </li></ul><ul><ul><li>Thermal </li></ul></ul><ul><li>A student listens to a CD player </li></ul><ul><ul><li>Electromagnetic and mechanical </li></ul></ul><ul><li>A teacher talks loudly to a classroom to get their attention </li></ul><ul><ul><li>Mechanical </li></ul></ul><ul><li>Hamburger that has been eaten at lunch </li></ul><ul><ul><li>Chemical </li></ul></ul>