A rigid body rotates about a fixed axis with a constant angular acceleration. Which one of the following statements is true concerning the tangential acceleration of any point on the body?

a. The tangential acceleration is zero m/s^2.
b. The tangential acceleration depends on the change in the angular velocity.
c. The tangential acceleration is constant in both magnitude and direction.
d. The tangential acceleration depends on the angular velocity.
e. The tangential acceleration is equal to the centripetal

To solve this problem it will be necessary to apply the concepts related to angular acceleration and tangential acceleration. Definitions are given in the description of the angular kinematic movement and describe these two expressions of acceleration as:

The angular acceleration of the object is written as,

The tangential acceleration is

Therefore equating the two previously expression we have,

Here we can conclude that the angular acceleration depends on the change in angular velocity.

Therefore the correct answer is B.

the working equation for the angular size is the product of the physical size and 360 degrees divided by the product of two pi and distance from earth. the minimum size would be 0.559 degrees while the maximum size would be 0.49 degrees. 

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.