Hot Air in a Physics Lecture. (a) A typical student listening attentively to a physics lecture has a heat output of 100 W. How much heat energy does a class of 140 physics students release into a lecture hall over the course of a 50-min lecture? (b) Assume that all the heat energy in part (a) is transferred to the 3200 m 3 of air in the room. The air has specific heat 1020J/kg·K and density 1.20 kg/m 3 . If none of the heat escapes and the air conditioning system is off, how much will the temperature of the air in the room rise during the 50-min lecture? (c) If the class is taking an exam, the heat output per student rises to 280 W. What is the temperature rise during 50 min in this case?
Hot Air in a Physics Lecture. (a) A typical student listening attentively to a physics lecture has a heat output of 100 W. How much heat energy does a class of 140 physics students release into a lecture hall over the course of a 50-min lecture? (b) Assume that all the heat energy in part (a) is transferred to the 3200 m 3 of air in the room. The air has specific heat 1020J/kg·K and density 1.20 kg/m 3 . If none of the heat escapes and the air conditioning system is off, how much will the temperature of the air in the room rise during the 50-min lecture? (c) If the class is taking an exam, the heat output per student rises to 280 W. What is the temperature rise during 50 min in this case?
Hot Air in a Physics Lecture. (a) A typical student listening attentively to a physics lecture has a heat output of 100 W. How much heat energy does a class of 140 physics students release into a lecture hall over the course of a 50-min lecture? (b) Assume that all the heat energy in part (a) is transferred to the 3200 m3 of air in the room. The air has specific heat 1020J/kg·K and density 1.20 kg/m3. If none of the heat escapes and the air conditioning system is off, how much will the temperature of the air in the room rise during the 50-min lecture? (c) If the class is taking an exam, the heat output per student rises to 280 W. What is the temperature rise during 50 min in this case?
A classroom has dimensions 8.00 m x 10.00 m x 3.00 m. A 1000 W electric space
heater is being used to warm the room from 5.00°C to 20.00°C on a cold morning. If
the density of air is 1.29 kg/m°, and the specific heat capacity of air is 1004 J/(kg-K),
how long will it take to heat the room? Assume no loss of thermal energy to the
surroundings.
A) 1.30 minutes
B) 241 minutes
C) 45.3 minutes
O D) 77.7 minutes
Geologists measure conductive heat flow out of the earth by drilling holes (a few hundred meters deep) and measuring the temperature as a function of depth. Suppose that in a certain location the temperature increases by 20°C per kilometer of depth and the thermal conductivity of the rock is 2.5 W/m·K. What is the rate of heat conduction per square meter in this location? Assuming that this value is typical of other locations over all of earth's surface, at approximately what rate is the earth losing heat via conduction? (The radius of the earth is 6400 km.)
Thermal energy is being transferred through a 0.8 mm layer of human skin at a rate of 1.1 x 104 W/m2. The room temperature is 27 °C.To reduce heat flux, the skin is wrapped with a clothing material. What should be the thickness of the clothing material covering the surface of this skin tissue to reduce the heat flux to half of its original value? What is the temperature at the skin-clothing material interface?
Note: if you think you need to have more information to solve this problem, you can make assumptions. Please state them clearly in your answer, if you need to make such assumptions.And please explain step by step to the answer to better understanding
Chapter 17 Solutions
University Physics with Modern Physics (14th Edition)
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