Figure 13.5 shows the working of simple wheel and axle. It consists of a wheel A of larger diameter and axle B of smaller diameter. Both wheel A and axle B are keyed to the same shaft. There are two strings—first is wound around the wheel A to which effort is applied and second is wound on axle B in reverse direction to which load is tied. When the effort is applied in the downward direction on wheel A, the string unwinds from wheel A and at the same time, second string winds on axle B and load W is lifted in upward direction.
Figure 13.5 Simple Wheel and Axle
The number of revolution of both wheel and axle per unit time will be same, since both are keyed to the same shaft.
Suppose the diameter of the wheel is D and of axle is d, load lifted is W, and effort applied is P.
The distance moved by the effort in one revolution of wheel A, y = πD and the distance moved by the load in one revolution of axle B, x = πd.
If thickness of the string t1 and t2 are to be considered, then
Practically, the thickness of string in comparison to wheel and axle is considered as negligible. Hence
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