In an old house, the heating system uses radiators, which are hollow metal devices through which hot water or steam circulates. In one room the radiator has a dark color (emissitivity = 0.830). It has a temperature of 64.1 oC. The new owner of the house paints the radiator a lighter color (emissitivity = 0.426). Assuming that it emits the same radiant power as it did before being painted, what is the temperature (in degrees Celsius) of the newly painted radiator?

Why is the following situation impossible? A group of campers arises at 8:30 a.m. and uses a solar cooker, which consists of a curved, reflecting surface that concentrates sunlight onto the object to be warmed (as shown). During the day, the maximum solar intensity reaching the Earth’s surface at the cooker’s location is I = 600 W/m2. The cooker faces the Sun and has a face diameter of d = 0.600 m. Assume a fraction f of 40.0% of the incident energy is transferred to 1.50 L of water in an open container, initially at 20.0°C. The water comes to a boil, and the campers enjoy hot coffee for breakfast before hiking ten miles and returning by noon for lunch.

A copper rod has a length of  1.5m1.5m and a cross-sectional area of 4.0×10−4m24.0×10−4m2. One end of the rod is in contact with boiling water and the other with a mixture of ice and water. What is the mass of ice per second that melts? Assume that no heat is lost through the side surface of the rod. Take the thermal conductivity of copper to be k=401W.m.Kk=401W.m.K, and the latent heat of fusion of ice to be 3.35×105J/kg3.35×105J/kg.

A metal rod is 10 cm long and has a diameter of 2 cm one end is in contact with steam at 100 deg C while the other end contacts a block of ice at 0 deg C. The cylindrical surface of the rod is carefully insulated so heat flows only from one end to end. In a time of 20 minutes, 320 grams of ice melts. What is the thermal conductivity of the metal?

A common practice for a person with a high fever is to take a bath in cool water. Assuming an 80 kg person is really ill and needs to cool down from 40°C to 37°C. What is the minimum amount of water needed for bathing assuming the water begins at room temperature, 25°C? The specific heat of the body on average is 3470 J/kg°C and water is 4186 J/kg°C.   16.6 kg   212.2 kg   200 kg   19.8 kg

What is the rate of heat transfer by radiation, with an unclothed person standing in a dark room whose ambient temperature is 22.0ºC . The person has a normal skin temperature of 33.0ºC and a surface area of 1.50 m2 . The emissivity of skin is 0.97 in the infrared, where the radiation takes place.

Animal tissue helps prevent excessive heat loss by conduction. In species 1, the outer tissue has thermal conductivity k1, cross-sectional area A1, and thickness x1. In species 2, the outer tissue has thermal conductivity k2, cross-sectional area A2, and thickness x2. For the same difference between internal and external temperatures, how is the rate of heat loss in species 2 (P2) related to that in species 1 (P1)? Group of answer choices P2 = (A1/A2) (x1/x2) (k2/k1) P1 P2 = (A2/A1) (x1/x2) (k2/k1) P1 P2 = (A1/A2) (x2/x1) (k2/k1) P1 P2 = (A2/A1) (x2/x1) (k2/k1) P1 P2 = (A2/A1) (x1/x2) (k1/k2) P1

A cubical piece of heat-shield-tile from the space shuttle measures 0.13 m on a side and has a thermal conductivity of 0.065 J/(s·m·C°). The outer surface of the tile is heated to a temperature of 1070°C, while the inner surface is maintained at a temperature of 24°C. (a) How much heat flows from the outer to the inner surface of the tile in 4.0 minutes? (b) If this amount of heat were transferred to 2.6 liters (2.6 kg) of liquid water, by how many Celsius degrees would the temperature of the water rise?

The exhaust duct from a heater has an inside diameter of 114.3 mm with ceramic walls 6.4 mm thick. The average k = 1.52 W/mK. Outside this wall, an insulation of rock wool 102 mm thick is installed. The thermal conductivity of the rock wool is k = 0.046+1.56*10-4T (°C) (W/mK). The inside surface temperature of the ceramic is T1= 588.7 K, and the outside surface temperature of the insulation is T3= 311 K. Calculate the heat loss for 1.5 m of duct and the interface temperature T2between the ceramic and the insulation.Assumesteady heat transfer.Hint: The correct value of km for insulation is that evaluated at the mean temperature of T2+T3/2. Hence, for the first trial assume a mean temperature of, say, 448 K. Then, calculate the heat loss and T2. Using this new T2, calculate a new mean temperature and proceed as before.

22. In an old house, the heating system uses radiators, which are hollowmetal devices through which hot water or steam circulates. In one roomthe radiator has a dark color (emissivity 5 0.75). It has a temperatureof 62 8C. The new owner of the house paints the radiator a lighter color(emissivity 5 0.50). Assuming that it emits the same radiant power as itdid before being painted, what is the temperature (in degrees Celsius) ofthe newly painted radiator?