The inner surface of a 0.25m thick brick wall of a furnace is kept at 810ºc, when the outside surrounding air is at 22ºc. the convective heat transfer coefficient of the outer surface is 12 w/m2k and the thermal conductivity of the brick is 0.865 w/mk. neglect the convective resistance for the inner side of the furnace and assume that the problem is steady state and thermal radiation is neglected. (a)-sketch the system and calculate the rate of heat loss per unit wall area. (b)-calculate the temperature of the outer wall surface.

Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.