Aman can row at 6kmhr in still water and want to cross a river to a position exactly opposite his starting point. if the river is 5km wide and his flowing at 4kmhr eastward. find by scale drawing or other wise direction in which he must set off in order to accomplish his objective. how long will it take to cross the river

if the river is 5km wide and is flowing at 4km/hr. eastwards find by scale ... Find either by scale drawing or by calculation (1) the direction in which he must ... He could row his boat directly across the river to point C and then run to B, or he ... A man who can swim at 5km/h in still water swims towards the east to cross arriver.

Explanation:

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.