A house has well-insulated walls 19.5 cm thick (assume conductivity of air) and area 410 m 2 , a roof of wood 5.5 cm thick and area 280 m 2 , and uncovered windows 0.65 cm thick and total area 33m 2 . ( a ) Assuming that heat is lost only by conduction , calculate the rate at which heat must he supplied to this house to maintain its inside temperature at 23°C if the outside temperature is −15°C. ( b ) If the house is initially at 12°C, estimate how much heat must be supplied to raise the temperature to 23°C within 30 min. Assume that only the air needs to be heated and that its volume is 750m 3 ( c ) If natural gas costs $0.080 per kilogram and its heat of combustion is 5.4 × 10 7 J/kg, how much is the monthly cost to maintain the house as in part ( a ) for 24 h each day, assuming 90% of the heat produced is used to heat the house? Take the specific heat of air to be 0.24 kcal/kg · C°.
A house has well-insulated walls 19.5 cm thick (assume conductivity of air) and area 410 m 2 , a roof of wood 5.5 cm thick and area 280 m 2 , and uncovered windows 0.65 cm thick and total area 33m 2 . ( a ) Assuming that heat is lost only by conduction , calculate the rate at which heat must he supplied to this house to maintain its inside temperature at 23°C if the outside temperature is −15°C. ( b ) If the house is initially at 12°C, estimate how much heat must be supplied to raise the temperature to 23°C within 30 min. Assume that only the air needs to be heated and that its volume is 750m 3 ( c ) If natural gas costs $0.080 per kilogram and its heat of combustion is 5.4 × 10 7 J/kg, how much is the monthly cost to maintain the house as in part ( a ) for 24 h each day, assuming 90% of the heat produced is used to heat the house? Take the specific heat of air to be 0.24 kcal/kg · C°.
A house has well-insulated walls 19.5 cm thick (assume conductivity of air) and area 410 m2, a roof of wood 5.5 cm thick and area 280 m2, and uncovered windows 0.65 cm thick and total area 33m2. (a) Assuming that heat is lost only by conduction, calculate the rate at which heat must he supplied to this house to maintain its inside temperature at 23°C if the outside temperature is −15°C. (b) If the house is initially at 12°C, estimate how much heat must be supplied to raise the temperature to 23°C within 30 min. Assume that only the air needs to be heated and that its volume is 750m3 (c) If natural gas costs $0.080 per kilogram and its heat of combustion is 5.4 × 107 J/kg, how much is the monthly cost to maintain the house as in part (a) for 24 h each day, assuming 90% of the heat produced is used to heat the house? Take the specific heat of air to be 0.24 kcal/kg · C°.
a wall consist of 3.0 cm of exterior wood and 2.0 cm of interior wood spearated by a 15cm layer of polystyrene foam. if the interior is kept at 19 Celsius degree, calculate the outside temperature for which the heat loss through the is 10 W/m2
The convection heat transfer coefficient for a clothedperson standing in moving air is expressed as h = 14.8V 0.69for 0.15 < V < 1.5 m/s, where V is the air velocity. For aperson with a body surface area of 1.7 m2 and an averagesurface temperature of 29°C, determine the rate of heat lossfrom the person in windy air at 10°C by convection for airvelocities of (a) 0.5 m/s, (b) 1.0 m/s, and (c) 1.5 m/s.
Suppose a human body's core internal temperature is 37.0°C, the skin temperature is 34.0°C, the thickness of the tissues between averages 0.95 cm, and the surface area is 1.435 m2.
-Calculate the rate of heat conduction, in watts, out of the human body.
Chapter 19 Solutions
Physics for Scientists and Engineers, 4th Ed + Masteringphysics: Chapters 20-35
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