Given the result of Eq. (10.43), find the relation for the balloon radius given a constant \overline{\nu }_{s}. 4\pi r^{2}\frac{dr}{dt}=\overline{\nu }_{s}\pi a^{2},
Given the result of Eq. (10.43), find the relation for the balloon radius given a constant \overline{\nu }_{s}. 4\pi r^{2}\frac{dr}{dt}=\overline{\nu }_{s}\pi a^{2},
Equation (10.43) can be written as
\left[r(t)\right]^{2}\frac{dr}{dt}=\frac{\overline{\nu }_{s}a^{2} }{4}.Hence, integrating from time t=0 to time t, we have
\int_{0}^{t}{\left[r(t)\right]^{2} }\frac{dr}{dt}dt=\int_{0}^{t}{\frac{\overline{\nu }_{s}a^{2} }{4} }dt,
or
\frac{\left[r(t)\right]^{3} }{3}-\frac{\left[r(0)\right]^{3} }{3}=\frac{\overline{\nu }_{s}a^{2} }{4}t
and, thus,
r(t)=\left(\left[r(0)\right]^{3}+\frac{3\overline{\nu }_{s}a^{2} }{4}t \right)^{1/3}.