The inclined plane (Sample Problem 11-1) is a simple “machine” that enables us to do work with the application of a smaller force than is otherwise necessary. The same statement applies to a wedge, a lever, a screw, a gear wheel, and a pulley combination (Problem 3). Far from saving us work, however, such machines in practice required that we do a little more work with them than without them. Why is this so? Why do we use such machines?

The inclined plane is a simple machine that enables us to do work with the application of a smaller force than is otherwise necessary. If you were to raise the block vertically at constant speed without using the incline, the work you do would be the vertical component of the force you exert on the block, which is equal to mg, times the vertical distance h. The only difference is that the incline permits a smaller force to raise the block than would be required without the incline. On the other hand, the distance you must push the block up the incline is greater than the distance you would move it if you raised it directly. That is why, we use such machines.