* Do work with one movement Simple Machines * Do work with one movement

Six Types: - Inclined plane - Wedge - Screw - Lever - Wheel and axle - Pulley

Inclined Plane A flat, sloped surface Allows you to exert your input force over a longer distance. Mechanical advantage = length of incline height of incline

Wedges Wedge- a device that is thick on one end and tapers to a thin edge at the other end. It is a movable inclined plane. Example: ax, zipper Mechanical Advantage: length of wedge width of wedge

Screw Screw – an inclined plane wrapped around a cylinder The threads of a screw act like an inclined plane to increase the distance over which you exert an input force. The closer the threads of a screw the greater the mechanical advantage. Mechanical advantage – the length around the threads the length of the screw

Levers Lever- a rigid bar that is free to pivot, or rotate on a fixed point. The fixed point is called the fulcrum. Example: Paint can opener Mechanical advantage = distance from fulcrum to input force distance from fulcrum to output force

1st class levers Fulcrum is between input force and output force (object) Examples: see-saw, scissors, crowbar

2nd class levers Output force (object) is between the fulcrum and the input force. Examples: wheelbarrows, doors, nutcrackers

3rd class levers Input force is between the output force (object) and the fulcrum Examples: shovel, fishing pole, your arm

Wheel and axle Wheel and Axle- two circular or cylindrical object fastened together that rotate about a common axis. Examples: Ferris wheels, bicycles, door knobs, screw driver Mechanical Advantage = radius of the wheel radius of axle

Pulleys Pulley- a grooved wheel with a rope or cable wrapped around it. Input force is applied by pulling on one end of the rope which; Decreases the amount of input force needed by applying it over the distance of the rope Can change the direction of your input force Ex. flagpole

Types of Pulleys Fixed pulley – a pulley attached to a stationary structure; only changes direction of the force Mechanical Advantage = 1 Movable pulley – multiplies input force, but does not change direction Mechanical Advantage >1 Block and Tackle – system made up of fixed and moveable pulleys

Increasing Mechanical Advantage of a pulley The longer the rope the longer the distance the input force is applied over, so the greater the mechanical advantage. Mechanical Advantage of a pulley system = the number of supporting sections of a rope

Compound Machines A combination of two or more simple machines Ex. Apple peeler