A man, the surface area of whose skin is `2m^(2)` , is sitting in a room where air temperature is `20^(@)C` if his skin temperature is `28^(@)C` and emissivity of his skin equals 0.97, find the rate at which his body loses heat.

Calculate radiationn powe for sphere whose temperature is 227^(@)C and radius 2 m and emissivity 0.8.

A scientist says that the efficiency of his heat engine which operates at source temperature 127^(@)C and sink temperature 27^(@)C is 26% , then

A body radiates heat at the rate of 5 cal/ m^(2)-s when its temperature is 227^(@)C . The heat radiated by the body when its temperature is 727^(@)C is

Water is filled in a vessel which is kept in a room at a temperature of 20^(@)C . The temperature of the water is slowly increased. When the temperature of water is 40^(@)C , it loses heat at the rate of 10cal/s. What will be the rate of loss of heat when the temperature of water is 80^(@)C ?

An object is being heated by a heater supplying 60W of heat. Temperature of surrounding is 20^(@)C and the temperature of object becomes constant at 50^(@)C Now the heater is switched off What is the rate at which the object will lose heat when its temperature has dropped to 30^(@)C .

A blackbody of sarface area 10cm^(2) is heated to 127^(@)C and is suspended in a room at temperature 27^(@)C calculate the initial rate of loss of heat from the body to the room.

(a) Calculate the rate at which body heat is conducted through the clothing of a skier in a steady-state process, given the following data : the body surface area is 1.8m^(2) , and the clothing is 1.0 cm thick , the skin surface temperature is 33^(@)C and the outer surface of the clothing is at 1.0^(@)C , the thermal conductivity of the clothing is 0.040 W//m . K. (b) If , after a fall, the skier's clothes became soaked with water of thermal conductivity 0.60 W//m.K , by how much is the rate of conduction multiplied ?