Physics is a complex field, requiring lots of math and thought to know thoroughly. A relatively easy part of physics to understand are the simple machines.
There are six different simple machines. The simple machines include inclined planes, wedges, levers, wheels and axles, screws, and pulleys. Most are used daily. Simple machines allow humans to complete tasks with less effort.
They do this by altering forces to perform work. Work is defined as the transfer of energy by a force. Whenever you move something, you are doing work.
Types of simple machines
Inclined planes consist of a ramp. By sliding objects along the ramp as opposed to lifting them, you decrease the amount of force required to move them. The trade-off this comes with is that the object has to travel further horizontally.
A lever is a stiff beam that rotates around a fixed point (the fulcrum). Moving one end of the lever moves the other end in the opposite direction. Examples of levers include bottle openers, crowbars, and seesaws.
Pulleys use a fixed set of wheels (the pulley) attached to a cord that allows you to change the direction a force is applied to an object. By combining the power of multiple pulleys, a large mechanical advantage is created. Curtain cords and wells use pulleys. Elevators function with the help of a number of pulleys.
A screw is similar to an inclined plane wrapped around a central point. Rotating the threaded shaft of a screw causes movement in either direction. Faucets and lightbulbs are examples of screws.
A splitting action is converted from a force by wedges. Wedges might be used to raise or cut objects. Knives and log splitters are two kinds of wedges.
With the combination of a wheel and a central fixed axle, a force is transformed into a greater force as it travels from the edge of the wheel to the center of the axle. Two examples of wheel and axle systems are bikes and steering wheels.
Simple machines and animals
Some simple machines play a part in the human body. A select few body parts mimic a number of simple machines. For example, the shoulder can function both as a wheel and axle and as a lever. Shoulder joints rotate similar to a wheel and axle, and they can easily lift like a lever. Wrist joints can twist like a screw, allowing us to open jars.
Actions done by body parts can also qualify as simple machines. When a human uses a corkscrew to open a bottle of wine, the corkscrew serves as a lever. Grinding maize with a mortar and pestle is an example of the use of a wedge. Riding a bike down a hill takes advantage of an inclined plane.
Indeed, simple machines are more prevalent in daily life than you might have initially expected.
We use simple machines to help us complete tasks. Blinds open and close with the help of a pulley. Scissors take advantage of a wedge to cut. While it might seem obvious, construction work and home projects using screws uses… screws.
Other intelligent animals also use simple machines. Crows use stones as wedges, and otters use rocks as hammers.
Simple machines are even found throughout nature. Instead of the typical ball-and-socket appendage joint, the Papuan weevil has legs that are screwed into place. A wedge-like force is exerted when water freezes in a crack; freezing water can split rocks.
Making my own machines
Since we now know that simple machines are ubiquitous in the world, it is probably easy to believe me when I say there’s a few simple home experiments you can conduct to further observe simple machines at work! Here are just some of the ways to make simple machines at home.
Gears are a kind of wheel and axle. You can create your own gears by flattening bottle caps of various sizes, then poking holes in the center. Affix the bottle caps onto a board so that the teeth on each cap intersects with the teeth on another. When you turn one bottle cap, what happens to the rest?
Experience how the length of a lever and the location of its fulcrum influence the amount of force it takes to use the lever with the help of a coin and a spoon. Place the coin at the handle end of the spoon and launch the coin, then place the coin at the spoon end and repeat. Which way did the coin go further?
A wedge can be quickly constructed from a solid piece of wood. By placing the wood block under a log, you have wedged something underneath the log, lifting it. Can you still wedge the wood under a log while someone is standing on it?
You can fashion a pulley out of a plastic container, string, scissors, and magnets and paper clips to see how this makeshift pulley can be useful. Glue magnets to the bottom of the container. Cut two holes in the container’s walls, directly across from each other. Thread a string through the holes and tie it at the top, making a triangle of string with the plastic container running across the bottom edge. Thread that triangle through another longer string, making a loop, then hang the loop around somewhere it can rotate from, like a door handle. Place paper clips under the pulley system and move the container as needed to pick up the paper clips.
Make a ramp out of a cereal box on top of towers of Lego. A ramp is an example of an inclined plane. You can race toy cars or marbles down your new ramp! What materials travel fastest and slowest on the ramp?
You can build a screw, which again is an inclined plane wrapped around a cylinder, for more marble fun. Take paper plates and cut holes in the center. Cut a slit from the outside edge to the inner circle in each plate. Tape the plates together to make a spiral. Hot glue the chain of plates, with each plate spaced evenly apart, onto an empty wrapping paper tube. Now you have a spiral marble ramp – a screw!
Beyond these demonstrations, ask your children or students about everyday examples of simple machines that they can think of, as there are many more than what’s listed in this article! What is your favorite simple machine?
Comment and share below.