2. I. What is a Machine? A. Machine is anything that helps us do work. B. They multiply or change the direction of force

3. C. Mechanical advantage: measures the efficiency of the machine D. In the real world, no machine is 100% efficient E. This is because of friction

4. II. Simple Machines A. There are 6 types of simple machines. 1. Lever: bar that pivots around a fulcrum a. 1 st class b. 2 nd class c. 3 rd class

5. 2. Pulley: grooved wheel and some sort of cord or rope 3. Wheel & Axle: round object that rotates around a rod

6. 4. Ramp: an inclined plain 5. Wedge: triangular shape used for splitting things 6. Screw: inclined plain wrapped around a central core

7. II. What are Compound Machines? A. combination of any 2 or more simple machines B. Examples: 1. axe 2. wheel barrow