Approximate the human form as an unclothed vertical cylinder of 0.3 m diameter and 1.75 m length with a surface temperature of 30 oC.(a)Calculate the heat loss in a 10 m/s wind at 20 oC.(b)What is the heat loss if the skin is covered with a thin layer of water (i. e., sweat) at 30 oC and the relative humidity of the air is 60 %

As part of an industrial process, air as an ideal gas at 10 bar, 400k expands at steady state through a valve to a pressure of 4 bar. the mass flow rate of air is 0.5 kg/s. the air then passes through a heat exchanger where it is cooled to a temperature of 295k with negligible change in pressure. the valve can be modeled as a throttling process, and kinetic and potential energy effects can be neglected. (a) for a control volume enclosing the valve and heat exchanger and enough of the local surroundings that the heat transfer occurs at the ambient temperature of 295 k, determine the rate of entropy production, in kw/k. (b) if the expansion valve were replaced by an adiabatic turbine operating isentropically, what would be the entropy production? compare the results of parts (a) and (b) and discuss.

Astudent wears sunglasses to her read a book more easily which wave interaction occurs as light passes from the air into the plastic lenses? a polarization b. refraction c. diffraction d. interference

If the spring constant k of a pogo stick is 3500 n m and the weight of the person on the pogo stick is 700 n, how much is the spring in the botom of the pogo stick compressed?