A concrete has a height of 5m and has unit area 3m² supports a mass of 30000kg. Determine the stress, strain and change in height ​

stress = 98000 N/m^2

strain = 3.92 x 10^-6

change in height = 0.0196 mm

Explanation:

Height, h = 5 m

Area, A = 3 m²

mass, m = 30000 kg

Stress is defined as the force per  unit area.

Young's modulus of concrete is Y = 2.5 x 10^10 N/m^2

Young's modulus is defined as the ratio of stress to the strain.

let the change in height is h'.

Strain is defined as the ratio of change in height to the original height.

and 1and 1

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.