A spherical ball of solid, nonporous naphthalene, a ‘‘moth ball’’, is suspended in still air. The naphthalene ball slowly sublimes, releasing the naphthalene into the surrounding air by molecular diffusion-limited process. Estimate the time required to reduce the diameter from 2 to 0.5 cm when the surrounding air is at 347Kand 1.013 × 105 Pa. Naphthalene has a molecular weight of 128 g/mol, a solid density of 1.145 g/cm3, a diffusivity in air of 8.19 × 10−6 m2/s, and exerts a vapor pressure of 5 Torr (666 Pa) at 347 K.

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.

If the thermal strain developed in polyimide film during deposition is given as 0.0044. assume room temperature is kept at 17.3 c, and thermal coefficient of expansion for the film and the substrate are 54 x 10^-6c^-1 and 3.3 x 10^-6c^-1respectively. calculate the deposition temperature.

Which of the following is an easy way to remember the modified “x” tire rotation? a. nondrive wheels straight, cross the drive wheels b. drive wheels straight, cross the nondrive wheels c. drive wheels crossed, nondrive wheels straight d. drive wheels crossed, nondrive wheels crossed