Question 19 How much force in Newtonsis exerted on rigid walls by an alloy bar of length 1.4m and crosssectional area of 0.2m2 fitting snugly between the walls when the temperature rises by 25C. The coefficient of linear expansion of the metal alloy is 2106 and its Young's modulus is 41010Nm2. \begin{tabular}{|l|} \hline Question 20 \\ Sam attaches a falling 493Kg sack with a rope through a pulley to a paddle wheel shaft. He plices the \\ system in a well-insulated tank holding 49Kg of water. When the sack falls it cases the padile whed \\ to rotate and chum the water. If the sack falls a vertical distance of 62 at a constant speed, what is the \\ temperature in C change of the water? ( 1 Klocalorie =4186J and g=9.8m/s2 ) \\ \end{tabular}