Aperson runs up several flights of stairs and is exhausted at the top. later the same person walks up the same stairs and does not feel as tired. ignoring air resistance, does it take more work to run up the stairs than to walk up?

Explanation:

Work done by the person depends on its mass and the height raised. It also depends on the acceleration due to gravity.

As the height raised and the mass of person is same. The value of acceleration due to gravity is also constant So, the work done is also same in both the cases.

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.