Question 1:

a) The heat flux through a wood slab 50 mm thick, whose inner and outer surface temperatures are 40 and 20 ?C, respectively, has been found to be 40W/m2. Calculate the thermal conductivity.

b) A plate (5 cm x 10 cm), as shown in Figure 1 is maintained at 100 ?C and heat is lost to the surrounding of temperature, 25 ?C. Given that the convective heat transfer coefficient is 5 W/m2K. Calculate the total heat transfer from the plate. Assume the thickness of the plate to be very small compared to the area.

c) Explain how heat transfer occurs in solids.

10 Cm 5 cm Figure 1 A thin plateQ T C D A O 1 m 3 m 2 m Figure 2 Forces on a beam