1. C HAPTER 12 W ORK AND E NERGY Section 2 Simple Machines p. 385

2. O BJECTIVES Understand simple machines Evaluate the relationship between energy, work, and power

3. I. Lever Family A. Levers 1. 1 st Class 2. 2 nd Class 3. 3 rd Class IF OF IF OF IF OF

4. B. Pulley – modified lever C. Wheel and Axle- pulley/lever connected to a shaft (MA=diameter of wheel/diameter of axle) 1. Fixed pulley- MA = 1 It just changes the direction 2. Moveable pulley system- MA= # of ropes or # of pulleys + one

5. II. Inclined Plane Family A. Inclined plane- multiply and redirect force 1. Output is the force needed to lift the object straight up to the objective 2. Spreads input force out over a longer distance B. Wedge- modified plane (2 inclined planes back-to-back) C. Screw- inclined plane around a cylinder

6. III. Compound Machine- 2 or more simple machines in one machine

7. C HAPTER 12 W ORK AND E NERGY Section 3 What is Energy? p. 391

8. I. Energy- ability to do work, measured in Joules II. Potential Energy A. PE- the energy an object has because of its position, shape, or condition (Stored Energy) 1. Elastic PE 2. Gravitational PE

9. B. Gravitational PE 1. Depends on mass and height 2. Grav. PE= mass x free-fall acceleration x height PE = mgh (just like work)

10. III. Kinetic energy- energy of a moving object due to the motion A. KE depends on mass and speed KE= ½ mv 2 or KE = ½ J (J= kg x m 2 /s 2 ) B. KE depends more on speed than mass B. Gravitational PE 1. Depends on mass and height 2. Grav. PE= mass x free-fall acceleration x height PE = mgh (just like work)

11. IV. Mechanical Energy- sum of potential and kinetic energy – amount of work an object can do A. Will stay the same for the same object; just the amount of PE and KE will change

12. B. Non-mechanical Energy- energy at the molecular level that doesn’t affect motion 1. Chemical Energy- gasoline, bombs 2. Nuclear Energy- radiation, nuclear 3. Thermal Energy 4. Light (Electromagnetic) 5. Sound