Question

1(a)

State Fouriers Law, and define the terms in the equation, in each case giving the units for each term as well. What assumption is implied by the use of Fouriers Law concerning the heat flow through the mat and wooden surface?

(b)

An insulating mat is 8 mm thick and is placed on a wooden surface 15 mm thick. A large block of a hot material is placed on the mat. If the surface of the mat in contact with the heated block is at 100°C, and the temperature at the base of the wooden surface is at 25°C, use Fouriers Law to determine the temperature of the interface between the block and the mat. The mat has a thermal conductivity of 0.1 Wm-1K-1 and the wooden surface has a thermal conductivity of 0.5 Wm-1K-1.

(c)

Calculate the change in density if a steel block was heated from room temperature, (20°C), to 800°C. The coefficient of linear expansion for steel = 12 x 10-6 K-1, while the density of steel (at 20°C) = 7800 kgm-3.

Answer 1