Question A1 a. An insulated cylindrical copper rod of 20 mm diameter is heated at one end by a 100W cartridge heater set

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Question A1 A An Insulated Cylindrical Copper Rod Of 20 Mm Diameter Is Heated At One End By A 100w Cartridge Heater Set 1 (205.1 KiB) Viewed 9 times

Question A1 a. An insulated cylindrical copper rod of 20 mm diameter is heated at one end by a 100W cartridge heater set at full power and cooled at the opposite end. If the temperature drop along a 4 cm length of the bar is measured to be 31.75 °C, determine the thermal conductivity of the copper, assuming that all of the heat provided is transferred along the bar by conduction. (30%) Answer: k = 401 W/m.K b. A room is initially at the same temperature as the air outdoors, 10°C. A heater which consumes 1kW of electricity is switched on inside the room. If the exposed surface area of the room is 30m2 and the convection heat transfer coefficient from the outside of the room to the surroundings is 6 W/m².°C, calculate the equilibrium temperature reached in the room, assuming that the heater is 95% efficient. Neglect any heat transfer out of the room by conduction and radiation. (30%) Answer: 15.56°C C. An electric motor controlling a pump draws 3.6 A from a 12 v power supply. The mechanical power output measured using a dynamometer is found to be 30 W. Calculate the efficiency of the motor and suggest what could account for any losses. (40%) Answer: 69.4% (losses could include friction & heating of bearings and linkages)