A short brass cylinder $\left(\rho=8530 \mathrm{~kg} / \mathrm{m}^3, c_p=\right.$ $0.389 \mathrm{~kJ} / \mathrm{kg} \cdot{ }^{\circ} \mathrm{C}, k=110 \mathrm{~W} / \mathrm{m} \cdot{ }^{\circ} \mathrm{C}$, and $\alpha=3.39 \times$ $10^{-5} \mathrm{~m}^2 / \mathrm{s}$ ) of diameter $D=8 \mathrm{~cm}$ and height $H=15 \mathrm{~cm}$ is initially at a uniform temperature of $T_i=150^{\circ} \mathrm{C}$. The cylinder is now placed in atmospheric air at $20^{\circ} \mathrm{C}$, where heat transfer takes place by convection with a heat transfer coefficient of $h=40 \mathrm{~W} / \mathrm{m}^2 \cdot{ }^{\circ} \mathrm{C}$. Calculate (a) the center temperature of the cylinder; (b) the center temperature of the top surface of the cylinder; and (c) the total heat transfer from the cylinder 15 min after the start of the cooling.