Air at a temperature of 300 C flows with a velocity of 10 m/s over a flat plate 0.5 m long. Average Nusselt number to maintain plate-surface temperature at 27 C is calculated to be 57.4 by the equation given below: Nu, = 0.664 Re/2Pr1/3 = 57.4 Find the percentage of changes in the average heat convection coefficient for each of the following cases (assuming that everything else is the same as given in the problem statement): (a) When air velocity (u) is increased 4-fold? (b) When plate-length (L) is increased 4-fold? (c) When the heat conduction coefficient of the plate (kpl) is increased 4-fold?