1. a one-shell-pass and multiple-of-two tube passes heat exchanger is to be used to cool 12 kg/s of oil with an equal flow rate of water. the heat exchanger area of the heat exchanger is 40 m2. the inlet temperatures of the oil and water are thi = 100 c and tci = 20 c, respectively. the specific heats of the oil and water are 2.09 kj/kg. k and 4.18 kj/kg. k, respectively. the total heat transfer coefficient is controlled by the side and is 1000 w/ m2.k. determine the exit temperature of the oil and water.

frequency or wavelenth of em radiation in a vacuum

d. air pressure decreases as altitude increases.

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.