Mechanical advantage is a term that is used to describe the amount of force that is utilized internally by some sort of mechanical device. It allows the device to perform the task for which it was designed. Many common tools that are used in the home and in construction make use of this principle.
One of the best ways to understand this idea is to consider the simple action that takes place between a screwdriver and a screw. Force is exerted on the screwdriver, causing the body of the tool to rotate, while at the same time pressing the screw into some sort of surface, such as a wooden block. The combination of rotational force and forward movement make it possible for the screwdriver to use mechanical advantage to secure the screw into the medium.
Another example has to do with the use of crushing machines. Mechanisms of this type make use of two flat surfaces. An object is placed between those two surfaces, and using simple hydraulic action, the top surface is moved in the direction of the lower surface. As it moves closer, the factor of mechanical advantage makes it possible to compact the volume of the object into a smaller space.
In general, it is understood that there are two distinct concepts of this principle. The first is known as ideal mechanical advantage, normally referred to as IMA, and it has to do with the creation and function of an ideal machine. Since no truly ideal machine currently exists, the concept remains theoretical, but is helpful in making calculations.
The second is known as actual mechanical advantage or AMA, and it deals with the use of real machines that function in the physical world. Here, such working factors as the amount of energy that is lost due to the friction generated during a given task is taken into consideration when calculating the rate of mechanical advantage.