Simple machines are practically a part of every device you can think of. Without these machines, we would all still be living in caves.
Two types of works are involved in using a machine. One of these is the work that goes into the machine, which is called work input. It comes from the force that is applied to the machine, or the effort force. You put work into the machine that you use as you exert effort over some distance. The machine does work too. It exerts a force, called an output force, over some distance. The work dome by the machine is called work output. The work output is used to overcome the force you and the machine are working against.
Machines do not increase the work you put into them. The work that comes out of a machine can never be greater than the work that goes into it. In reality, the work output is always less than the work input. This is because friction is always involved in the operation of any machine. Friction is the force that acts in the opposite direction of motion and can cause an object to slow down and finally stop. Some of the work the machine does is used to overcome friction. Comparing the work output to work input will help you determine the efficiency of a machine. The closer the work output is to the work input, the more efficient the machine. Efficiency is expressed as a percentage and it can never be greater than 100%. In fact, many attempts have been made to create a perpetual motion machine (a machine which is 100% efficient), but so far this has proved impossible.
There are just six simple machines. They are the lever, wheel and axle, pulley, inclined plane, wedge and screw. Actually, the wheel and axle and the pulley are different forms of lever, and the wedge and the screw are different forms of the inclined plane. All machines, no matter how many parts they have, are made up of one or more simple machines. Hence, they are called compound machines. Cars, bicycles and watches are some examples of compound machines. Most of machines we use everyday are compound machines. Compound machines make doing work easier and more enjoyable but remember that, as with simple machines, they cannot multiply work. The amount of work we get out of a machine can be no more than the amount of work you put into it. In the next articles, you can learn more about each of the six simple machines.
Machines would soon stop working without lubrication. The “father of lubrication” is Elijah McCoy, an African-American engineer. He designed a continuous drip lubrication process so that there would be no need to shut down large machinery just so it could be thoroughly lubricated.