A spaceship (consider it to be rectangular) is of size 7 x 4 x 4 (in meters). Its interior is maintained at a comfortable 20C, and its outer surface is at 116.9 K. The surface is aluminum. Calculate the rate of heat loss by radiation into space, if the temperature of outer space is 2.1 K. (

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

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A 12-cm x 18-cm circuit board houses on its surface 100 closely spaced logic chips, each dissipating 0.06 W in an environment at 40°C. The heat transfer from the back surface of the board is negligible. If the heat transfer coefficient on the surface of the board is 10 W/m2.K, determine (a) the heat flux on the surface of the circuit board, in W/m2;

A homeowner is unhappy with her heating costs. One wall of her house is 4 meters tall and 8 meters wide and has no windows, and it is made of brick and mortar with a thermal conductivity of 1.0 W m K . It is 40 cm thick. The house is heated to a temperature of 20 ◦C inside. (a) What is the rate of heat loss through the wall on a day when it is 0◦C outside? (b) A layer of rock mineral wool, which has a thermal conductivity of 0.032 W m K is to be installed on the interior surface of the brick wall. How thick should the layer be to lower the rate of heat transfer through this wall to half its original value? (c) If the rock mineral wool is instead installed on the outer surface, is the thickness required the same?

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?