To measure the specific heat in the liquid phase of a newly developed cryoprotectant, you place a sample of the new cryoprotectant in contact with a cold plate until the solution’s temperature drops from room temperature to its freezing point. Then you measure the heat transferred to the cold plate. If the system isn’t sufficiently isolated from its room-temperature surroundings, what will be the effect on the measurement of the specific heat? (a) The measured specific heat will be greater than the actual specific heat; (b) the measured specific heat will be less than the actual specific heat; (c) there will be no effect because the thermal conductivity of the cryoprotectant is so low; (d) there will be no effect on the specific heat, but the temperature of the freezing point will change.
To measure the specific heat in the liquid phase of a newly developed cryoprotectant, you place a sample of the new cryoprotectant in contact with a cold plate until the solution’s temperature drops from room temperature to its freezing point. Then you measure the heat transferred to the cold plate. If the system isn’t sufficiently isolated from its room-temperature surroundings, what will be the effect on the measurement of the specific heat? (a) The measured specific heat will be greater than the actual specific heat; (b) the measured specific heat will be less than the actual specific heat; (c) there will be no effect because the thermal conductivity of the cryoprotectant is so low; (d) there will be no effect on the specific heat, but the temperature of the freezing point will change.
To measure the specific heat in the liquid phase of a newly developed cryoprotectant, you place a sample of the new cryoprotectant in contact with a cold plate until the solution’s temperature drops from room temperature to its freezing point. Then you measure the heat transferred to the cold plate. If the system isn’t sufficiently isolated from its room-temperature surroundings, what will be the effect on the measurement of the specific heat? (a) The measured specific heat will be greater than the actual specific heat; (b) the measured specific heat will be less than the actual specific heat; (c) there will be no effect because the thermal conductivity of the cryoprotectant is so low; (d) there will be no effect on the specific heat, but the temperature of the freezing point will change.
The concrete slab of a basement is 11 m long and 8 m wide, and 0.20 m thick. During the winter, temperatures are
nominally 17°C and 10°C at the top and bottom surfaces, respectively. If the concrete has a thermal conductivity of 1.4
W/mK, what is the rate of heat loss through the slab? If the basement is heated by a gas furnace operation at an
efficiency of 90%, and natural gas is priced at $0.02. MJ, what is the daily cost of the heat loss.
Answer: QLOSS = 4.312 kW, COST = $8.28/day
Jill takes in 0.0140 mol of air in a single breath. The air is taken in at 20.0°C and exhaled at 35.0°C.
Her respiration rate is (1.30x10^1) breaths per minute. At what average rate does heat leave her body due to the temperature increase of the air? Provide your answer to three significant figures.
HINT: Use the molar specific heat at constant volume to find the heat loss, where Cv = 5R/2 (for an ideal diatomic gas).
Thermography is a technique for measuring radiant heat and detecting variations in surface temperatures that may be medically, environmentally, or militarily meaningful.(a) What is the percent increase in the rate of heat transfer by radiation from a given area at a temperature of 34.0C compared with that at 33.0C, such as on a person’s skin? (b) What is the percent increase in the rate of heat transfer by radiation from a given area at a temperature of 34.0C compared with that at 20.0C, such as for warm and cool automobile hoods?
Chapter 17 Solutions
University Physics with Modern Physics Plus Mastering Physics with eText -- Access Card Package (14th Edition)
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