Sometimes, students don't realize how much science is all around us every day. For instance, simple machines, which include pulleys, wheels and axles, levers, inclined planes, screws, and wedges, combine to create cars, which are compound machines. By examining each simple machine found in cars, the overall machine becomes less mysterious but even more interesting. Learning about each type of simple machine can help students understand not only how cars work but how many other things work in their world.
Inclined planes are more commonly known as ramps. An inclined plane is a flat piece of hard material that can be used to raise or lower a load. Wheelchair ramps, slides, and stairs are all examples of inclined planes. This is a great simple machine that students can identify in their day-to-day life.
A lever is a simple machine that uses a rigid beam along with a fulcrum. When force is applied to one end of the beam, the fulcrum serves to move the load. Levers rely on torque for their operation. Students might be surprised to learn that the parking brake of a car is a type of lever.
Pulleys are another type of simple machine that can reduce the amount of force that is required to move an object. By combining pulleys, students can learn how different angles, distances, and other factors contribute to the effectiveness of a pulley system. Pulleys make a fun project for students to build on their own to witness the workings of a simple machine.
A screw is an inclined plane wrapped around a pole. This is a simple machine that students will be surprised to hear is considered a machine. A screw can be used to move things or hold things in place. Screws are most often used in conjunction with other simple machines.
A wedge is a simple tool that is basically a moveable inclined plane. Examples of wedges in everyday life include nails, knives, and axes. A wedge is a triangular piece of material that works by combining the force applied from two different directions. Students have used wedges their whole life without realizing it, as their teeth are a type of wedge!
A wheel and axle consists of two disks of different sizes that rotate together around the same axis. This is probably the most easily identifiable simple machine for many students.
Compound machines are created when simple machines are combined for one purpose or several related purposes. Students can wrap up a unit on simple machines by creating a compound machine to serve a specific purpose. Try having the class compete in groups to see whose compound machine can move or lift the heaviest weight. They might even try creating a Rube Goldberg device, combining all of the different simple machines into one fun, silly contraption.