Along 24 cm diameter shaft of stainless steel 304 (kstst = 13.72 w/m. k, rho = 7721 kg/m^3, cp = 490 j/kg. k) comes out from an oven at a uniform temperature of 636°c. the shaft is then exposed to a cross flow of air (ka = 45.89 w/m. k, rho = 0.6964 kg/m^3, cp = 1034 j/kg. k) at a velocity of 20 m/s and temperature of 218°c with a convection coefficient of h = 48.74 w/m^2.k. (a) how long does it take for the shaft to have a minimum temperature of 388°c? (b) calculate the maximum temperature of the shaft at that time as in part (a).

Heat is added to a piston-cylinder device filled with 2 kg of air to raise its temperature 400 c from an initial temperature of t1 27 cand pressure of pi 1 mpa. the process is isobaric process. find a)-the final pressure p2 b)-the heat transfer to the air.

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.

If a particle moves along a path such that r : (3 sin t) m and ? : 2t rad, where t is in seconds. what is the particle's acceleration in m/s in 4 seconds? a)- 16.43 b)- 16.29 c)- 15.21 d)- 13.79