Two plane disks each 1.25 m in diameter are parallel and directly opposite each other. they are separated by a distance of 0.5 m. disk 1 is heated by electrical resistance to 833.3 k. both disks are insulated on all faces except the two faces directly opposite each other. assume that the surroundings emit no radiation and that the disks are in space. calculate the temperature of disk 2 at steady state and also the electrical energy input to disk 1. (hint: the fraction of heat lost from area number 1 to space is 1 – f12.)

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.

Refrigerant 134a enters an insulated compressor operating at steady state as saturated vapor at -26°c with a volumetric flow rate of 0.18 m3/s. refrigerant exits at 9 bar, 70°c. changes in kinetic and potential energy from inlet to exit can be ignored. determine the volumetric flow rate at the exit, in m3/s, and the compressor power, in kw.

Coiled springs ought to be very strong and stiff. si3n4 is a strong, stiff material. would you select this material for a spring? explain.