A force of 150 N is continuously applied to an object with a mass of 11 kg over a distance of 2.5 m. The object slides over a surface with a coefficient of kinetic friction of .3.How fast is the object moving immediately after the force ceases to be applied?

Final velocity will be 7.31 m/sec

Explanation:

We have given applied force F = 150 N

Mass of the object m = 11 KG

Distance traveled by the object s = 2.5 m

Coefficient of kinetic friction

Acceleration due to gravity

So frictional force applied on the object

So net force = 150-32.34 = 117.66 N

As work done us equal to

So work done =

Now according to work energy theorem work done is equal to change in kinetic energy

So

v =7.31 m/sec

So velocity final velocity will be 7.31 m/sec

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.