A circular disk of diameter Di 20 mm is located at the base of an enclosure that has a cylindrical sidewall and a hemispherical dome. The enclosure is of diameter D-0.5 m, and the height of the cylindrical section is L 0.3 m. The disk and the enclosure are black and at temperatures 1000 K and 300 K, respectively.

(a) What is the net rate of radiation exchange between the disk and the hemispherical dome?
(b) What is the net rate of radiation exchange between the disk and top third of the cylindrical section (e. g. the section of the cylindrical sidewalls between the hypothetical surfaces Azand A3)?

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.

The thermal expansion or contraction of a given metal is a function of the f a)-density b)-initial temperature c)- temperature difference d)- linear coefficient of thermal expansion e)- final temperature f)- original length

The characteristic roots of a dynamic system are: 1.7920 1.8160 i, -1.7920 1.8160 i, -0.4160 what is the order of this system? what are the settling time and damping ratio of the system?