Machines are devices generated to direct, regulate or take advantage of the action of a certain force. They usually work from the energy they receive and then transform to generate a specific effect. Machines can be classified based on various criteria. Some are:
1) According to its complexity:
- Simple machines. They are usually made up of a single piece. For example a tweezer, a nail clipper, a knife.
- Complex machines. They have several pieces. For example an excavator, a car engine.
- Very complex machines. They are made up of many pieces. For example a jet engine, a space rocket.
2) According to the number of steps they require to carry out their work:
- Simple machines. They carry out their work in one step, which makes their operation very easy to explain and understand. For example an ax, a pair of scissors, a wheel, a ramp.
- Composite machines. They need to perform various jobs in a chained manner. They are made up of several simple machines that work continuously. It is very difficult to explain how it works. For example the computer, a satellite, a printer.
3) According to the type of propulsion they use :
- Manual machines. They do not have an engine but rather work from mechanisms that are actuated from thrust. They are inexpensive, quiet, and do not require a lot of maintenance. For example an ax, a clamp.
- Machines with an electric cable. They need an electrical current to function and are characterized by being able to work continuously. In addition, they do not generate noise or smoke and are usually easy to transport. The downside is that the cable limits where they can be used. For example a lawnmower, an electric saw.
- Battery-powered machines. They do not emit smoke or noise. The fact that they work with batteries does not determine the place where they can be used. They are usually more expensive and their operation is limited by the life of the batteries, which is between three and seven hours. For example: a remote control.
- Powered machines. They generate smoke and noise but can run continuously.