Atransistor, which may be approximated as a hemispherical heat source of radius ro 0.1 mm, is embedded in a large silicon substrate (k 125 w/m k) and dissipates heat at a rate q. all boundaries of the silicon are maintained at an ambient temperature of t 27 c, except for the top surface, which is well insulated.
obtain a general expression for the substrate tempera ture distribution and evaluate the surface temperature of the heat source for q = 4 w

Ahot wire operates at a temperature of 200°c while the air temperature is 20°c. the hot wire element is a tungsten wire of 5 um diameter and 2 mm in length. plot using excel current, heat transfer and heat generated by the wire for air velocity varying from 1-10 m/s in steps of lm/s? matlab the sensor voltage output, resistance, or assume nu 0.989 re033pr13 take air properties at tr (200°c20°c)/2 = 110°c properties of tungsten: c 0.13 kj/kg.k 3 p 19250 kg/m k (thermal conductivity) = 174 w/m.k

Asolid cylinder is concentric with a straight pipe. the cylinder is 0.5 m long and has an outside diameter of 8 cm. the pipe has an inside diameter of 8.5 cm. the annulus between the cylinder ad the pipe contains stationary oil. the oil has a specific gravity of 0.92 and a kinematic viscosity of 5.57 x 10-4 m2/s. most nearly, what is the force needed to move the cylinder along the pipe at a constant velocity of 1 m/s?

Agas mixture consists of 8 kmol of h2 and 2 kmol of n2. determine the mass of each gas and the apparent gas constant of the mixture.