An element on a hot stove is maintained at a constant temperature of Thot = 105 °C and a pan is placed on the element. The base of the pan can be taken to be a uniform circular layer of diameter 15 cm and thickness 7.0 mm, and with a thermal conductivity of 15 W m-1 K-1. a. The air above the pan comes into thermal equilibrium with the element. Write down the temperatures on the top and bottom surfaces of the pan and the rate of heat flow through the pan. Use the zeroth law of thermodynamics to explain your answer. A fan is then switched on so that the air above the pan is maintained at Tcold = 20 °C, and the system reaches a steady state. b. Identify the heat transfer mechanism that is being used to maintain the air at Tcold. c. Calculate the rate of heat transfer through the pan. A 3.0 mm thick layer of soup is added to the pan and the system again reaches a steady state. The temperature at the boundary between the pan and the soup is 95 °C. d. Find the thermal conductivity of the soup, assuming that it spreads evenly over the entire base of the pan. e. Explain why the density of water is unusual as it is heated up from 0 °C.
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An element on a hot stove is maintained at a constant temperature of Thot = 105 °C and a pan is placed on the element. The base of the pan can be taken to be a uniform circular layer of diameter 15 cm and thickness 7.0 mm, and with a thermal conductivity of 15 W m-1 K-1.
a. The air above the pan comes into thermal equilibrium with the element. Write down the temperatures on the top and bottom surfaces of the pan and the rate of heat flow through the pan. Use the zeroth law of
A fan is then switched on so that the air above the pan is maintained at Tcold = 20 °C, and the system reaches a steady state.
b. Identify the heat transfer
c. Calculate the rate of heat transfer through the pan.
A 3.0 mm thick layer of soup is added to the pan and the system again reaches a steady state. The temperature at the boundary between the pan and the soup is 95 °C.
d. Find the thermal conductivity of the soup, assuming that it spreads evenly over the entire base of the pan.
e. Explain why the density of water is unusual as it is heated up from 0 °C.
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