My Simple Stories

Complex machines are so much part of everyday life that is easy to forget that they actually operate on very simple principles. With the help of simple such as the lever and the pulley, which increase or redirect the force of our muscles, we can perform work than would be impossible with our bare hands. In everyday life we make use of a huge range of machines from giant cranes to moving escalator sand even the humble bicycle. But all machines, no matter how complex, use the basic principles of simple machines, especially the lever. Lever can act not only in straight lines but can multiply forces as they rotate. For instance, in a wind turbine, the rotor harnesses wind power and transfers it to a central axle (shaft). Although the axle rotates through the same angle as the end of the rotor blade, it moves a much smaller distance. This means that the relatively small force from the wind as it pushes the end of the blade through a large distance is translated into a much stronger force at the axle. The power in the axle that came from a puff of the wind can be used to turn a generator.

In almost every situation there is a machine to help make work easier. The most common machines are some of the simplest. There is a huge range of machines. These mechanical devices that make possible all kinds of human activities include machines that convert energy from one form to an other, as in the car’s gasoline engine which converts the stored chemical energy of gasoline into energy of motion. The word machine is also used for things that merely process information, such as television sets and computers. A simple machine is something very specific. It is a device that can carry force from one place to another, change its direction, or change its strength. The crowbar used to lift a paving stone is a simple machine. Another simple machine is the screw: its action is seen clearly in the car jack, which converts the force of the person’s hand turning a  handle into a force large enough to lift a car. Similarly, the woodscrew is driven into wood by the weak force of fingers turning a screwdriver. Simple machines that multiply force have one thing in common: if they are to work the force has to be moved farther than the load is moved. The hand pressing on the crowbar moves about 10 minutes as far as the corner of the paving stone that is raised. The hand on jack handle moves a long way (because it makes many turns) to raise simple machines work. They convert a small force, effort, exerted over along, applied over a shorter distance. In fact, work done by the operator of a machine (effort times distance moved by effort) equals the work done on the object (load times distance moved by the load).