With all of the complex gadgets in our modern world, a “simple machine” may sound like an oxymoron. Much like a “jumbo shrimp” or a “working vacation”, a “simple machine” may not make a lot of sense.
But, simple machines are the oldest and most useful human tools. They include things like the inclined plane, the lever, the wedge, the screw, and the pulley.
What is a simple machine?
Simple machines can be built easily with very few or no moving parts. Many of the complicated machines we use today are based on the designs of simple machines.
A simple machine is a mechanism that allows humans to magnify the force they can apply by spreading it out over a distance or to change the direction of the force.
Curious about how this is possible? Check it out…
Types of Simple Machines
There are six types of simple machines. Let’s take a look at how each type works:
Inclined Plane
An inclined plane is a flat surface that tilts up at an angle. Ramps are inclined planes. Moving an object up an inclined plane takes less energy per step than moving the load up all at once. Instead of exerting a ton of energy to lift the load straight up, less energy is used in many steps to slowly work the load up to the proper height. By spreading the force over a distance, moving an object up an inclined plane takes less force than lifting it directly.
Lever
A lever is a flat surface that sits on a fulcrum. The ends of the lever move up and down while the center sits on the fulcrum.
The lever reduces the amount of force needed to lift heavy objects. By sticking one end of a lever under a heavy object and pressing down on the other end of the lever you are moving one end through a greater distance and reducing the force needed to lift the object. The lever is like a superpower: it gives you the ability to lift much more than you could on your own.
A seesaw is a lever. The support in the middle is the fulcrum. If you have ever played on a seesaw, you have used this simple machine!
Wedge
A wedge is an elongated, triangular tool with one thin edge. An ax is a type of wedge. Wedges transform downward force into outward force. A wedge is similar to two inclined planes put together. For example, when you use an ax to chop wood, you bring the ax down and it forces the wood to split in two.
Screw
The screws you find in a toolbox are an example of this simple machine. A screw is a cylinder that has a raised rib spiraling down it, almost like an inclined plane wrapping around.
Pulley
If you’ve ever been in an elevator, you’ve been moved by a pulley!
A pulley is a wheel with a cord around it. A pulley allows you to change the direction of the force you apply.
You can magnify the force you apply with a pulley by using larger pulley with a smaller one. Using the greater distance of the larger wheel you can apply greater force to the smaller wheel.
Wheel and Axle
The wheel is one of the most important human inventions. But the wheel isn’t nearly as useful without the axle. An axle is a rod with a wheel on each end, designed to allow the wheels to spin. Once you have both a wheel and an axle, you can really move because wheels reduce friction.
Think about the difference between dragging a tree branch on the ground and dragging the same tree branch in a wagon. The wheels and axles of the wagon reduce all of the friction, making the branch much easier to move.
Written by Laura McCamy
Edited by Gabriel Buckley, MS Professional Natural Sciences
Illustrated by Pablo Velarde Diaz-Pache