Problem 6.240

Evaluate the amount of heat produced during a day by a \(\beta\) -active \(\mathrm{Na}^{24}\) preparation of mass \(m=1.0 \mathrm{mg} .\) The beta-particles are assumed to possess an average kinetic energy equal to \(1 / 3\) of the highest possible energy of the given decay. The half-life of \(\mathrm{Na}^{24}\) is \(T=15\) hours.