Sonar is used to locate objects underwater by measuring the time it takes an ultrasound sound pulse to reflect back to the receiver. An oceanic depth-sounding vessel surveys the ocean bottom with ultrasonic sound that travels 1530 m/s in seawater. Find the depth of the water if the time delay of the echo to the ocean floor and back is 8 seconds.

The floor of the ocean is 6120 m deep.

Explanation:

In order to find the depth of the ocean we need to use the speed of the ultrasonic sound 1530 m/s and the time it takes for the echo to comeback. Since the wave is transmitted by the vessel goes to the bottom of the ocean and comeback, it travels the distance between the vessel and the floor two times, so we can divide the time by two. We then have:

D = V*t/2 = 1530*8/2 = 1530*4 = 6120 m

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.