A soap bubble is blown to a diameter of 7 cm. 36960 erg of work is done in blowing it further. If surface tension of soap solution is 40 dyne / cm…

A soap bubble is blown to a diameter of $\displaystyle 7$ cm. $\displaystyle 36960$ erg of work is done in blowing it further. If surface tension of soap solution is $\displaystyle 40$ dyne $\displaystyle / \mathrm{cm}$ then the new radius is $\displaystyle \_\_\_\_$ cm Take $\displaystyle \left(\pi=\frac{22}{7}\right)$.