The best example of this is the bicycle, by which we gain speed by exerting a greater force. Machines are also used to change the direction of a force. For example, the Signalman s halyard enables one end of the line to exert an upward force on a signal flag while a downward force is exerted on the other end. The wheel and axle, block and tackle, and gears may be considered levers. The wedge and the screw use the principle of the inclined plane.
Complex machines are merely combinations of two or more simple machines.
The simplest machine, and perhaps the one with which you are most familiar, is the lever. A seesaw is a familiar example of a lever in which one weight balances the other. Look at the lever in figure 1-1. Distances A and a are the arms of the lever. Integrated Publishing's Official Web Page Click here for a current index of everything on this web site.