In a cold winter, you went outside and touched a material. In the material (let
ID: 1850452 • Letter: I
Question
In a cold winter, you went outside and touched a material. In the material (let us say this is material A), you were surprised because you felt that the temperature of the material A is almost the same as your body temperature. The material had been outside for a while so temperature of it should be the same as the outside temperature. Explain how this is possible and present a required relationship for this to be possible. For your reference, thermal conductivity, density and specific heats of the material A and your body are kA, ?A & cA, and kB, ?B, & cB respectively.Explanation / Answer
The temperature of the surface of the cooling body depends upon the strength of the draught of air Even when the air convection is only due to heating of the layer in contact with the solid surface the temperature is much lower than the temperature inside the body. In fact if there is no gradient, there won’t be cooling at all. dQ/dt=-kA(t2-t1)/d if (t2-t1)/d value is low or no graident vary in bosy the temparature remains constant