A closed box is filled with dry ice at a temperature of -89.2 C, while the outside temperature is 28.0 °C. The box is cubical, measuring 0.297 m on a side, and the thickness of the walls is 2.88 x 10-2 m. In one day, 3.08 x 106 J of heat is conducted through the six walls. Find the thermal conductivity of the material from which the box is made. Number i Units

A closed box is filled with dry ice at a temperature of -89.2 C, while the outside temperature is 28.0 °C. The box is cubical, measuring 0.297 m on a side, and the thickness of the walls is 2.88 x 10-2 m. In one day, 3.08 x 106 J of heat is conducted through the six walls. Find the thermal conductivity of the material from which the box is made. Number i Units

College Physics

11th Edition

ISBN:9781305952300

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter11: Energy In Thermal Processes

Section: Chapter Questions

Problem 50P: A Styrofoam box has a surface area of 0.80 m and a wall thickness of 2.0 cm. The temperature of the...

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A glass windowpane in a home is 0.620 cm thick and has dimensions of 1.00 in 2.00 in. On a certain day, the temperature of the interior surface of the glass is 25.0C and the exterior surface temperature is 0C. (a) What is the rate at which energy is transferred by heat through the glass? (b) How much energy is transferred through the window in one day, assuming the temperatures on the surfaces remain constant?
A glass coffee pot has a circular bottom with a 9.00-cm diameter in contact with a heating element that keeps the coffee warm with a continuous heat transfer rate of 50.0 W (a) What is the temperature of the bottom of the pot, if it is 3.00 mm thick and the inside temperature is 60.0C ? (b) If the temperature of the coffee remains constant and all of the heat transfer is removed by evaporation, how many grams per minute evaporate? Take the heat of vaporization to be 2340kJ/kg.
The surface area of an unclothed person is 1.50 m2, and his skin temperature is 33.0C. The person is located in a dark room with a temperature of 20.0C, and the emissivity of the skin is e = 0.95. (a) At what rate is energy radiated by the body? (b) What is the significance of the sign of your answer?
Beryllium has roughly one-half the specific heat of water (H2O). Rank the quantities of energy input required to produce the following changes from the largest to the smallest. In your ranking, note any cases of equality, (a) raising the temperature of 1 kg of H2O from 20C to 26C (b) raising the temperature of 2 kg of H2O from 20C to 23C (c) raising the temperature of 2 kg of H2O from 1C to 4C (d) raising the temperature of 2 kg of beryllium from 1C to 2C (e) raising the temperature of 2 kg of H2O from -1C to 2C
(a) How much heat transfer is required to raise the temperature of a 0.750-kg aluminum pot containing 2.50 kg of water from 30.0 to the boiling point and then boil away 0.750 kg of water? (b) How long does this take if the rate of heat transfer is 500 W?
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The thermal conductivities of human tissues vary greatly. Fat and skin have conductivities of about 0.20 W/m K and 0.020 W/m K, respectively, while other tissues inside the body have conductivities of about 0.50 W/m K. Assume that between the core region of the body and the skin sin face lies a skin layer of 1.0 mm, fat layer of 0.50 cm, and 3.2 cm of other tissues. (a) Find the R-factor for each of these layers, and the equivalent R-factor for all layers taken together, retaining two digits. (b) Find the rate of energy loss when the core temperature is 37C and the exterior temperature is 0C. Assume that both a protective layer of clothing and an insulating layer of unmoving air a absent, and a body area of 2.0 m2.
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