(Solved): Question I: Answer the following questions: (a) How does the science of heat transfer differ from t ...

Question I: Answer the following questions: (a) How does the science of heat transfer differ from the science of thermodyramics? (b) What is the driving force for (a) heat transfer, (b) electric current flow and (c) fluid flow? (c) On a hot summer day, a student turns his fan on when he leaves his room in the morning. When he returns in the evening, will his room be warmer or cooler than the neighboring rooms? Why? Assume all the doors and windows are kept closed. Question \# 2: A 15 -cm-diameter aluminum ball is to be heated from \( 80^{\circ} \mathrm{C} \) to an average temperature of \( 200^{\circ} \mathrm{C} \). Taking the average density and specific heat of aluminum in this temperature range to be \( \rho= \) \( 2700 \mathrm{~kg} / \mathrm{m}^{3} \) and \( C_{p}=0.90 \mathrm{~kJ} / \mathrm{kg} \cdot \mathrm{K} \), respectively, determine the amount of energy that needs to be transferred to the aluminum ball. Question A 3: A plane wall with surface temperature of \( 350^{\circ} \mathrm{C} \) is attached with straight triangular fins \( (\mathrm{k}=235 \mathrm{~W} / \mathrm{m} \cdot \mathrm{K}) \). The fins are exposed to an ambient air condition of \( 25^{\circ} \mathrm{C} \) and the convection heat transfer coefficient is \( 154 \mathrm{~W}^{2} \mathrm{~m}^{2} \). K. Each fin has a length of \( 50 \mathrm{~mm} \), a base of \( 5 \mathrm{~mm} \) thick and a width of inn \( \mathrm{mm} \) D?termine the efficiency, and effectiveness of cach fin using Figure 2 Figure 2: Efficiency of straight fins of rectangular, triangutar, and paraoune pruance Question 1 4: A hollow spherical iron conteiner with outer diarneter \( 20 \mathrm{~cm} \) and thickness \( 0.2 \mathrm{~cm} \) is filled with iced water at \( 0^{\circ} \mathrm{C} \). If the outer surface temperature is \( 5^{\circ} \mathrm{C} \), determine the approximate tate of heat loss from the sphere, in \( \mathrm{kW} \), and the rate at which ice melts in the container. The heat of fusion of water is \( 333.7 \mathrm{~kJ} / \mathrm{kg} \). Question F 5: An electric current of 5 A passing throogh a resistor has a measured voltage of \( 6 \mathrm{~V} \), across the resistor. The resistor is cylindrical with a diameter of \( 2.5 \mathrm{~cm} \) and length of \( 15 \mathrm{~cm} \). The resistor has a uniform temperature of \( 90^{\circ} \mathrm{C} \) and the room air temperature is \( 20^{\circ} \mathrm{C} \). Assuming the heat transfer by radiation is negligible, determine the heat transfer coefficient by convection.