Simple Machines Week 8 Notes Chapter 4, Section 3 Pages 124 – 135

Simple Machines There are __6__ basic kinds of simple machines. The __INCLINE PLANE__, the __WEDGE__, the __SCREW__, the __LEVER__, the __WHEEL AND AXLE__, and the __PULLEY__.

Inclined Plane How it Works Mechanical Advantage An inclined plane is a __FLAT, SLOPED SURFACE__ How it Works An incline plane allows you to __EXERT__ your __INPUT FORCE__ over a longer distance. Input Force is __PUSHING or PULLING__ up the incline plane Output Force is the force needed to __LIFT__ the object Output Force is equal to the __WEIGHT__ of the object Mechanical Advantage M.A. = __LENGTH OF INCLINE__ / __HEIGHT OF INCLINE__ The __LONGER__ the incline, the __LESS__ input force you need to __PUSH__ or __PULL__ an object. Brain Pop: Inclined Plane (1:59)

Wedge How it Works Mechanical Advantage A __WEDGE__ is a device that is __THICK__ at one end and tapers to a __THIN__ edge at the other end. A wedge can be thought of as __2__ __INCLINED PLANES__ How it Works Using a wedge, __INSTEAD__ of moving an object along an __INCLINE PLANE__, you __MOVE__ the incline plane itself. Input Force is the wedge __MOVING__. Output Force is at a __90__ angle to its slope. Mechanical Advantage M.A. = __LENGTH OF WEDGE__ / __WIDTH OF WEDGE__ The __LONGER__ and __THINNER__ the wedge is, the __GREATER__ the M.A. http://www.youtube.com/watch?v=TAJT2usN-g8 (1:26)

Screws A __SCREW__ can be thought of as an __INCLINED PLANE__ wrapped around a cylinder. How it Works __TWISTING__ a screw you are __EXERTING__ an __INPUT FORCE__ on the screw. The __THREADS__ on a screw exert an __OUTPUT FORCE__ on the object, __PULLING__ the screw into the material. __FRICTION__ between the __SCREW__ and the __MATERIAL__ holds the screw in place. Mechanical Advantage M.A. = __LENGTH AROUND THE THREADS__ / __LENGTH OF THE SCREW__ The __CLOSER__ the threads are the __GREATER__ the mechanical Advantage. Eureka! Screw (1:35)

Levers How it Works Mechanical Advantage A __LEVER__ is a rigid bar that is free to __PIVOT__, or rotate, on a fixe point The fixed point that a lever pivots around is called the __fulcrum__ How it Works On the end of a __LEVER__ that you push down, you exert an __INPUT FORCE__ The lever pivots on the __FULCRUM__ The other side of the lever pushes up, as the __OUTPUT FORCE__ Mechanical Advantage M.A. = __DISTANCE FROM FULCRUM TO INPUT FORCE__ / __DISTANCE FROM THE FULCRUM TO OUTPUT FORCE__

Different Types of Levers Levers are classified by the __LOCATION__ of the __FULCRUM__ 1st Class Levers __ALWAYS__ change the direction of the input force In order: __OUTPUT FORCE __ __FULCRUM__ __INPUT FORCE __ 2nd Class Levers __INCREASE FORCE__, but do not change the direction of the input force. In order: __INPUT FORCE __, __OUTPUT FORCE __, __FULCRUM__ 3rd Class Levers __INCREASE DISTANCE__, but do not change the direction of the input force. In order: __FULCRUM__ __INPUT FORCE __ __OUTPUT FORCE __

Levers in the Body Brain Pop: Levers (2:40)

Wheel and Axle How it Works Mechanical Advantage __2__ circular or cylindrical objects fastened together that __ROTATE__ about a common axis. Larger radius is called the __WHEEL__ Smaller radius is called the __AXLE__ How it Works The __INPUT FORCE__ is exerted into the __WHEEL__ The __AXLE__ rotates and exerts a large __OUTPUT FORCE__ Mechanical Advantage M.A. = __RADIUS OF WHEEL__ / __RADIUS OF AXLE__ __RADIUS__ is the distance from the __OUTER__ edge of a circle to the circle’s __CENTER__ Brain Pop: Wheel and Axel (1:42)

Pulley A __PULLEY__ is a simple machine made of a grooved wheel with a rope or cable wrapped around it. How it Works __PULL__ on one end of rope = __INPUT FORCE__ __OUTPUT FORCE__ pulls up on the object you want to move Can __DECREASE__ the amount of input force needed to lift the object Can __CHANGE__ the direction of your input force.

Types of Pulleys __FIXED PULLEY__ does not change the amount of force applied. __CHANGES__ direction __MOVABLE PULLEY__ decreases the amount of __INPUT FORCE__ needed. __DOES NOT__ change direction __BLOCK AND TACKLE__ is a system made up of __FIXED__ and __MOVABLE__ pulleys M.A. is __EQUAL__ to the __NUMBER__ of sections of rope that support the object. Brain Pop: Pulley (2:09)

Compound Machines __COMPOUND MACHINES__ is a machine that utilizes __2__ or __MORE__ simple machines.