EngQuest 2010
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Simple Machines
This background information on Simple Machines is taken from the EngQuest 2010 website: www.engquest.org.au. Students use this information to construct various simple machines such as pull-along toys and catapults.
A machine is something that makes it easier for us to do work, such as moving objects. This happens when a force (a push or a pull effort) makes something (a mass or load) move for a distance. Simple machines are ones which have only one part to do the work. One example of a simple machine is a lever (see Diagram 1). The force applied to the lever (the crowbar) makes the rock move and the work easier to do.
More complicated machines (sometimes called Compound Machines) are made up of a number of simple machines that work together to help do the work. A wheelbarrow is one example of a compound machine. It has two levers (the handles) to help lift the load, and a wheel and axle to make it easier to move the load forward (see Diagram 2).
Load, effort and mechanical advantage
These are terms that are used to describe how simple machines work.
The load is the object that is moved. In Diagram 1, the load is the weight of the rock.
The effort is the force that is used to do the work. In Diagram 1, the effort is the force that the person applies to the crowbar to move the rock.
You can use a simple machine to move a large load with a smaller effort than you would need if you did not have a machine to help you. This is called gaining a mechanical advantage. If the rock in Diagram 1 weighed 100 kilograms, the lever might allow you to move it with a force of only 25 kilograms. The load would then be 4 times as big as the effort you applied, giving you a mechanical advantage of 4 (load divided by effort).
Types of Simple Machines
There are a number of different types of simple machines. These include:
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Compound machines are made up of a combination of these simple machines. Can you identify all the simple machines in the Simple Machines Animation?