2. Simple Machines

3. Friction Review Friction is the force we feel when things rub against each other The more things are pushed together, the more friction there is The more things are pushed together, the more friction there is It is the force that opposes motion.

4. Friction Review Friction slows down the movement of things and turns motion into thermal energy (heat). When you rub your hands together you can feel the thermal energy produced. The mucus from a slug will decrease friction as the slug slides along the ground.

5. Simple Machines The purpose of a simple machine is to A. increase the speed of work B. change direction the force is acting in C. increase Mechanical Advantage - a machine’s ability to multiply input force

6. Inclined Plane A flat surface placed at an angle to a horizontal surface:Examples: Ramp, roadways, slide, stairs

7. Lever A lever is a rigid bar that rocks back and forth at the fulcrum When a force is applied at one end, the other end moves. The object to be moved is the load

8. Types of Levers There are three types of levers: 1st class lever- fulcrum is between the force and the load: crowbar, seesaw, pliers 2nd class lever – load is between the force and the fulcrum: nutcracker 3rd class lever – load and fulcrum are at either end: broom, baseball bat, hammer

9. Wedge A wedge is made of 2 inclined planes put together A force is applied to the wedge to drive it into an object Examples: knife, chisel, nail, axe

10. Pulley A pulley is a wheel with a grooved rim for placement of a rope. A downward force on one side results in an upward movement on the other side. Examples: flagpole, curtain cord, mini-blinds

11. Two Types of Pulleys 1. 1. a fixed pulley – attached to an object 2. a moveable pulley – moves with the object

12. Screw A screw is a spiral inclined plane. Examples: jar lid, machine screw, mountain road

13. Wheel and Axle A bunch of levers pivoting around one fulcrum. A wheel or crank A wheel or crank attached to an axle. Examples: door knob, wheels of vehicles, gears

14. Compound (Complex) Machines A complex machine is made of two or more simple machines. Examples: Bicycle, wheel barrow, Rube Goldberg machine

15. List the simple machines in the Rube Goldberg complex machine that are numbered.