1. Energy Chapter 11 p.285 - 301

2. 11.1 – Forms of energy Energy is defined as the ability to do work. Heat energy (movement of molecules) ▫It is the sum of the kinetic energy of an object's molecules. Electrical energy (movement of electrons) ▫That is kinetic energy. The voltage in an electrical circuit is the potential energy that can start electrons moving. Electrical forces cause the movement to occur. Chemical energy (potential energy until the chemical reaction puts atoms and molecules in motion) ▫Heat energy (KE) is often the result of a chemical reaction. Light energy (movement of waves and/or light particles called photons) ▫It is usually formed when atoms gain so much kinetic energy from being heated that they give off radiation. This is often from electrons jumping orbits and emitting moving photons. Nuclear energy (internal forces in the nucleus) ▫When that potential energy is released, the result is kinetic energy in the form of rapidly moving particles, heat and radiation.

3. Kinetic vs Potential There are many different forms of energy, but the two main types are kinetic (energy of motion) and potential (energy of position) KE = ½ m v 2 PE = m g h(h is height, in meters) All previous forms of energy can be separated or defined by potential and kinetic energy.

4. Practice P.287 #1-3 P.291 #4-8 11.1 section review #10-13

5. 11.2 Conservation of Energy In a closed, isolated system energy can be neither created nor destroyed. Energy of a system = PE + KE KE = PE Read on p.294 about roller coasters, skiing, and pendulums Practice p.297 #15-18

6. Elastic collisions Super-elastic ▫Kinetic energy is larger after the collision  Ex. an explosion Elastic ▫Kinetic energy is conserved  Ex. atomic or nuclear particles with similar charges, magnets with similar poles facing each other, Super- Ball (like ‘Flubber’).  Ball bearings, a well inflated basketball, or any ball that bounces some is mostly elastic, but not completely.

7. Inelastic collisions Inelastic ▫Kinetic energy is smaller after the collision  Ex. An under-inflated basketball, or any ball that doesn't bounce much Completely inelastic ▫Kinetic energy is smaller, and the objects stick together, after the collision.  Ex. A block of soft clay dropped onto a hard floor, A bad car accident where the cars stick together, Two train cars collide and stick together.

8. Energy vs Momentum MOMENTUM IS ALWAYS CONSERVED Energy is only conserved in an elastic collision. When working problems, if the collision is inelastic, SOLVE USING MOMENTUM. ▫If energy is not conserved, there will be less energy after the collision than before. If the collision is elastic, you may use kinetic energy to solve.

9. Practice P.300 #19-21 11.2 Section review #24-28

10. Assignment Complete the second section of your Work, Power, and Energy worksheet ▫(Kinetic Energy and Potential Energy; #1-29)

11. Chapter Reviews Chapter 10 review ▫P.278-282 (#34-70 even, 79-85 all)  Extra credit: #89-93 Chapter 11 review ▫P.306-309 (#30, 33-41 all, 54-82 even) Due by the end of class Thursday 3/17 Test will be Monday 3/21