Adam is at the head of a large reservoir. the lake it forms is 20 km in length with a volume of 5 x 10^8 m^3. a.) what is the (gauge) pressure in the lake at the bottom of the dam? b.) a pipe with a diameter of 3.0m is open at the bottom of the dam. what is the velocity of the water that exists in the pipe? ( answer in mks units.) (the area of the circle is given by a = pi (d/2)^2, where d is the diameter of the pipe.

at positions a, g kinetic energy is maximum.

at position d, potential energy is maximum.

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.

option number c is the right answer.