to the work done in suddenly compressing the gas) from volume
to volume
.
Here we have
An Exercise.
Prove the ordinary mensuration formula, that the area
of a circle whose radius is
, is equal to
.
Consider an elementary zone or annulus of the surface (Fig 59), of breadth
, situated at a distance
from the centre. We may consider the entire surface as consisting of such narrow zones, and the whole area
will simply be the integral of all