An 15-cm-long bicycle crank arm, with a pedal at one end, is attached to a 21-cm-diameter sprocket, the toothed disk around which the chain moves. a cyclist riding this bike increases her pedaling rate from 62 rpm to 95 rpm in 12 s . a) what is the tangential acceleration of the pedal?

b)what length of chain passes over the top of the sprocket during this interval?

Explanation:

It is given that,

Length of the bicycle crank, l = 15 cm = 0.15 m

Diameter of sprocket, d = 21 cm

Radius, r = 0.105 m

Initial angular velocity,

Final angular velocity,

Time, t = 12 s

(a) The relation between the tangential acceleration and the angular acceleration. It is given by :

(b) Using third equation of kinematics as :

Let l is the length of the chain,

l = 10.35 m

Hence, this is the required solution.

im sorry i dont know

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.