3. a) By which mechanisms heat is conducted in solids, liquids and in gases? (1p) b) Use the transmissivity figure for SiO2 (main component in car windows) below to explain why car when left under direct sunlight acts as a heat trap and gets heated up from the interior? (1p) - Visible-7 1.0 0.8 0.6 TA 0.4 Thickness 0.038 cm 0.318 cm 0.635 cm 0.2 OL 0.25 0.4 0.60.1 1.5 3.1 4.7 6.3 7.9 Wavelength 2, um c) What is meant by the thermal contact resistance and what is its significance from the thermal management point of view? (1p) d) Determine the heat transfer through the composite wall shown in the figure below. Take the conductives of A, B, C, D & E as 50, 10, 6.67, 20 & 30 W/mK respectively and assume one dimensional heat transfer. Take of area of A =D=E = 1m and B=C=0.5 m. Temperature entering at wall A is 800 C and leaving at wall E is 100 C (2p). =