Abie L. Benítez
Humankind has used machines for centuries, many of which we would only consider tools today. The fact remains that machines, whether simple or compound, serve the purpose of aiding us to perform work in an easier or more efficient way. Machines transform energy sources into other kinds of energy to make them useful to us. For example, in a hydroelectric power station the kinetic energy that is contained in the water movement drives a turbine that powers a generator, thus turning kinetic energy into electricity.
To produce any action a machine needs a source of energy. In the past, many machines were powered by human and animal muscle power. Energy transferred to a screw by the action of muscle on a screw driver continues to be kinetic energy. There are other natural renewable sources that were used such as: wind and water. Who would not be impressed by the windmills in Holland or the Romans’ waterwheels? Although cleaner, non-renewable energy sources may not be as abundant as other sources which result from the work of scientist, inventors and engineers. Today the energy may come in the form of movement or electricity. For instance, the engine of a car converts heat energy into kinetic energy in such a way that it contributes to a more complex economy and has revolutionized the transportation systems.
Nowadays we find many machines powered by steam, gasoline and diesel engines which transform heat energy to mechanical energy. Although electricity is not a primary source of energy it has become a much used source of energy both at home and in industry, one that derives from other sources of energy such as coal or hydraulic power. An efficient machine gets the right amount of energy to the right place by using mechanical parts such as levers, gears, or pulleys. Machines can perform tasks that are beyond are physical power, thus the fascination we have with them.
Simple Machines
In order to understand how more complex machines work we must understand how simple machines have aided humans in performing tasks. The fact is that machines help us gain mechanical advantage, which is the factor by which a machine multiplies the force we put into it. The simple machines are easily identified by most people as tools that you may use in the day-to-day operation of a household.
The screw, the wedge and the lever are very common simple machines. For example, screw jack utilized to lift cars to change a flat tire. It is a lifting device that uses the principle of the screw and the lever by a small amount of effort to produce a large amount of force. The levers work under the principle that a small effort applied a long way from the fulcrum can lift a large load that is close to the fulcrum. Over two thousand years ago Archimedes, a Greek scientist explained how levers work and he said: “Give me a leverage point and I will move the world.” An ax that many utilize for wood cutting is a good example of a wedge but if you need an example of a more common wedge you can always show how a knife can cut through vegetables.
The inclined plane, another simple machine has aided civil engineers in building mountain roads that allow for us to travel with less effort than if we tried to climb straight up which would be almost impossible for our cars. Many of us have seen tow trucks lift and pull cars across town by using a pulley which is another simple machine and an axel and a wheel. For the purpose of this unit I am not going to expand on simple machines yet I want to show my students the advantages simple machines add to technological advances.
Compound machines I have discovered are a combination of more than one simple machine to perform a task such as: scissors. Because compound machines have more parts to it they have more mechanical advantage when compared to simple machines. Of greater advantage is a compound machine that is powered by an engine whether electric or mechanical these machines have changed our style of living. Such machines as cars, trucks, sewing machines, and others have made life more complex yet providing access to good or experiences we could not enjoy in the past.
