SIMPLE MACHINES! PULLEY!

What’s a Pulley?! A pulley consists of a rope or wire moving on a grooved wheel. The two sides of the pulley can be called the ‘effort/force arm’ and the ‘load arm’ Pulley’s are used to change the direction of a load force by: Raising a load Lowering a load

THREE TYPES OF PULLEYS 1. Fixed Pulley 2. Moveable Pulley 3. Combination Pulley

Fixed Pulley The fixed pulley is set up in ONE position usually to the top of a structure The fixed pulley allows objects to move but there is NO MECHANICAL ADVANTAGE The output force will be the same as the input force so the mechanical advantage is always 1

Moveable Pulley A moveable pulley is attached to and moves with the load that is being lifted Moveable pulleys allow you to move an object with less effort so the mechanical advantage is GREATER THAN 1

Combination Pulleys The more wheels that are added to a pulley, the more ropes that are required to lift a load. A combination pulley has more than 1 wheel This makes the mechanical advantage increase

To calculate the mechanical advantage of a compound pulley: You count the number of ropes connecting the pulley’s together EXCEPT the one your will be pulling on… Let’s look at some examples.

Examples: What is the mechanical advantage of this pulley and what would the effort force be if the load is 100 N? 100 N 1 2 This pulley has 2 ropes connecting it (not including the one you will be pulling on) so it has a mechanical advantage of 2 MA = 2, OF = 100 N, IF = ?

What is the mechanical advantage of this pulley and what would the effort force be if there was a load force of 300 N? 300 N 1 2 3 This pulley has 3 ropes connecting it (not including the one you will be pulling on) so it has a mechanical advantage of 3 MA = 3, OF = 300 N, IF = ?

What is the mechanical advantage of this pulley and what would the effort force be if there was a load force of 200 N? 200 N This pulley has 4 ropes connecting it (not including the one you will be pulling on) so it has a mechanical advantage of 4 MA = 4, OF = 200 N, IF = ?