1. You are working as a flight-test engineer at the NASA Dryden Research Center. During the low-speed phase of the test program for the X-37, you know that the plane is flying at an altitude of 8 km. The pressure at station 1 is 1550 N/m2, gage; the pressure at station 2 is -3875 N/m2, gage. a) If station 1 is known to be at the stagnation point, what is the velocity of the airplane? b) What is the freestream dynamic pressure for this test condition? c) Assuming inviscid flow, what is the velocity of the air at the second station relative to the airplane? What is the Cp for this station? d) What is the Equivalent Airspeed (EAS)?

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.

its a 5.5 n

glad that