Engineering Simple Machines
There was once a time that all man had to rely on was his own strength to accomplish his goals. It was through repeated struggle, trial and error, and engineering that man created simple tools to make tasks easier and less strenuous. Each simple tool has a very specific job and made work, a measurable amount of energy needed to move an object, easier.
A lever is one of the simplest tools designed to lift an object. It is made up of a rod or pole and a fulcrum. The fulcrum is a stationary, unmoving, object like a rock, that is placed under the pole or rod. The purpose of the fulcrum is to act as a brace, allowing for more force and leverage to be applied. The placement of the fulcrum in relation to the rod or pole determines how well the lever works. The closer the fulcrum is to the object that the person is trying to move, the easier the task will be. Examples of levers we see every day include light switches, door handles and hinges, and bottle openers.
The Inclined Plane (Ramp)
An inclined plane is another word for a ramp; one end of the ramp is lower to the ground than the other and this simple tool helps move objects between two different heights. Objects can be transported from low points to higher points, or in reverse, from higher to lower. Less force is needed to move objects using a ramp than vertically. Common ramps that we use every day include stairs, ladders, and slides.
The Wheel and Axle
Maybe one of the most important engineering marvels in human history is the wheel and axle. This simple machine revolutionized the way people lived and worked. Made up of a round wheel secured through the center with an axle, a rod or pole, the wheel spins on the axle and makes it easier to move objects on a flat surface or on an inclined plane. Wheel and axle simple machines that we see throughout the day might include those found on a bike, a revolving door, or on a car. Wheel and axle machines can also be motorized.
The pulley is one of the more advanced simple machines and it is actually a variation of a wheel and axle. A pulley is a wheel, centered on an axle, that uses a chain, rope, or another type of cord to move an object vertically or horizontally. The pulley reduces the energy needed to lift or move objects, be they light or heavy. Examples of a vertically-oriented pulley include a crane and an elevator. An example of a horizontally-oriented pulley would be a clothesline. Horizontally-oriented pulleys may also further reduce the work needed to move heavy objects up an inclined plane.
A wedge may look like a single inclined plane, but it is, in fact, two, and the wedge works very differently than a ramp. Wedges are used to forcefully separate an object. A very common example of this is an axe. On the flip side, a wedge can also be used to keep objects together. Examples of a wedge also include door stoppers and push pins.
The screw is a type of inclined plane, unique in that its twisted shape allows it to take up less space than a more horizontal plane. A screw can be used to move objects vertically and can be used to secure objects together. Examples of screws include swirly slides, mason jar lids, and - you guessed it - the screws you find at a hardware store.
Compound machines are more advanced than simple machines and typically combine two or more simple machines to work as one. Scissors are an example of a compound machine and combine a wedge and a lever. Likewise, a lawnmower is another simple machine that includes a wheel and axle and a wedge. Look around you and try to spot a compound machine and recognize the simple machines within it.
Simple Machine Resources