the mass of a brick is 4 kg, find the mass of water displaced by it when completely immersed in water.

Mass of water displaced = 1.6 kg

Explanation:

given data

Mass of brick m = 4kg

Density of water d₁ = 1000kg/m³

Density of brick d₂ = 2.5 g/cm³ = 2500 kg/m³

solution

we get here first volume of brick  that is

volume of brick =  m ÷ d₂     1

put here value and we get

volume of brick = 4 ÷ 2500

volume of brick = 0.0016 L

and

we will use here Archimedes' Principle formula of the buoyant force

as buoyant force = the weight of the liquid displaced by an object

so now we get here Buoyant Force that is express as

Buoyant Force = v × d₁ × g     2

put here value

Buoyant Force = 0.0016 × 1000 × 9.8

Buoyant Force = 15.68 Newtons

so

Buoyant Force = Weight of the water displaced     3

Buoyant Force = Mass of water displaced × g

and

weight = mass × acceleration due to gravity     4

so put here value and we will get

15.68 = mass of brick × 9.8

Mass of water displaced = 1.6 kg

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.