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# Simple Machines

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by

## Gus Allred

on 20 October 2014

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#### Transcript of Simple Machines

A fixed pulley is a simple machine that is a wheel and axle that has a groove for a rope or whatever is hanging on to the load to go through. The wheel hangs on to the place where you are lifting the load to. To lift the load on a fixed pulley, you must pull down on the side that is not holding the load. However, it does not allow you to use any less effort. For instance, if you are lifting a 300 pound weight, you still have to lift 300 pounds.
MOVABLE PULLEYS
A class three lever has the fulcrum on one end, the load on the other end, and the effort in the middle. Third class levers do not give any mechanical advantage. The force of effort is always greater than the force of the load. The effort is moved the same direction as the load. Class three levers usually have a motor to lift the load a greater distance. For example, a fishing rod's fulcrum is the reel, the middle of it is where you apply effort, and the line hangs on to the load, which is the fish, or whatever you catch with the fishing rod.
CLASS THREE LEVERS
A combination pulley is a fixed pulley and a movable pulley combined. You pull on one fixed/movable pulley. You pull down on a different fixed/movable pulley. Its the same as the other pulleys, except that it is more than one. For example, if you lift a load that weighs 600 pounds with one of the combination pulleys, you will have to lift 200 pounds because you have to use one third of the effort you use with a fixed pulley alone.
COMBINATION PULLEYS
Simple Machines

By: Gus Allred and Brayden Fryer

A simple machine is a device made to change the direction of effort use to move an object.

A class one lever is a beam, stick, or rod that sits on a fulcrum that is in the middle of it. The lever arm by itself does not help with anything. The load is on one end of the beam, stick, or rod. The effort is on the other end. Levers help lift things while using less effort. Using a class one lever, you push down to lift the load up. Class one levers can give you a mechanical advantage that is greater than 1. An example of a class one lever is that when you use fingernail clippers, the metal pole that you squeeze pushes a pin, which pulls together the two blades that clip your fingernails.
CLASS TWO LEVERS
A class two lever is also a beam, stick, or rod that sits on a fulcrum, but the fulcrum is on one end of it and the load is in the middle. With a class two lever, you have to apply effort on one end while the load is in the middle and the fulcrum is on the opposite end of the rod, stick, or beam. A class two lever does not give any mechanical advantage. With a class two lever, you need to pull up to lift the load instead of pushing down. For example, with a nutcracker, you have to squeeze in between the load and fulcrum. This cracks the nut.
FIXED PULLEYS
CLASS ONE LEVERS
WHEEL AND AXLE
An axle, or a rod that goes through the center of a wheel, carries loads with less effort than you would normally use. A wheel and axle can be used to multiply the distance by a lot. An axle is a lever that can rotate 360 degrees. If the wheel is bigger, you will have to use a lot less effort, but you will have to use effort for a lot longer. An example of a wheel and axle is a car. A car holds passengers and carries them long distances with little effort.
WEDGE
A wedge is a device used to move to things apart. A wedge has a sharp edge to cut or to pull two things away from each other. Things are easier to pull apart when the wedge's edge is thinner. One example of a wedge is a knife because a knife cuts things apart by pushing the things apart with its sharp edge.
SCREW
A screw has a round surface that can be twisted to unscrew things. A screw has a ridge that is not smooth, it's rough. Screws are used for holding objects together. An example of a screw is a lid on a jar because it twists on a jar with a rough ridge that runs around the outside of the lid.
WORK
What is work? Work is when you apply force to something and when you apply that force to another thing, it moves in the same direction that you apply the force to.