3. If the whistle has a sound intensity of 90 dB when the boat passes you 7 m away, how loud (in dB) is it in the cockpit just 1 m from the whistle

630dB

Explanation:

First you must know that the relationship between the sound intensity and the distance is an inverse relationship.

Let I represent the sound intensity

d represent the distance

Since I is inversely proportional to d, hence;

I ∝ 1/d

I = k/d

k is the constant of proportionality

If the whistle has a sound intensity of 90 dB when the boat passes you 7 m away, this means;

when I = 90dB, d = 7m

Substitute and get k first;

I = k/d

90 = k/d

k = 90 * 7

k = 630

To get how loud (in dB) is it in the cockpit just 1 m from the whistle, we will find I when d = 1 m

From the expression I = k/d

k = 630, d = 1

I = 630/1

I = 630dB

Hence the intensity is 630bB loud in the cockpit when it is just 1m from the whistle.

resonant frequency

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.