WHEEL AND AXLE

It is a simple machine and is used to lift heavy loads. It has a wheel of larger radius (R) and an axle of smaller radius (r) fixed on the same shaft. Wheel and axle is free to rotate about its shaft.

MECHANICAL ADVANTAGE OF WHEEL AND AXLE: -

The effort is applied to the rim of the wheel and the load is raised by a rope wound around the axle.

In one rotation wheel covers a distance of 2p R

In one rotation load is raised by a distance of 2p r

If we neglect force of friction,

Output = input

W x 2pr = P x 2pR

W/P = 2pR/2pr

W/P = R/r

Since [W/P = M.A.]

M.A. = R/r

OR

M.A. = radius of wheel / radius of axle

This expression indicates that in order to increase the mechanical advantage

·         Radius of: wheel must have a large value.

·         Radius of axle must be smaller than that of wheel.