In a collision an object experiences impulses , this impulse can be determined by

In a collision an object experiences impulses, this impulse can be determined by the product of net force exerted upon it in the specific course of time.

Explanation:

An object experiences impulse due to the force exerted upon it in a particular time period.

i.e.

Where,

F - Force acted upon the object

- time interval for which the force act

According to the definition of Impulse, it is the integral of force (F) that acts upon any object over a time interval ∆t. It produces an equivalent change in the momentum and that too in the same direction as of the applied force (F).

Therefore, in order to find the impulse on an object, we have to find the force acted on it in a specific time interval.

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.