Befor heating
`Mg = F_(b), Mg = V_(1)rho_(1)g = Axrho_(1)g` ……..(1)
After heating `Mg = F_(b)^(1), Mg = V^(1)rho_(1)^(1)g` ……(2)
Equating `(1)` & `(2) Axrho_(1)^(1)g`
`Arho_(1)g = A(l + betaDelta t)(rho_(1))/(1 + gammaDetla t)g`
`1 + gammaDelta t = 1 + betaDeltat, gamma = beta :. gamma = 2alpha`