No. I do not agree with Stefan. Quite the contrary. I disagree
with his description of "<span>angle of incidence" as the angle between
the surface of the mirror and the incoming ray.
The correct description of "angle of incidence" is </span><span>the angle between
the NORMAL TO the surface of the mirror and the incoming ray.
Thus, the true angle of incidence is the complement of the angle that
Stefan calculates or measures.</span>
Sound is all about vibrations.
The source of a sound vibrates, bumping into nearby air molecules which in turn bump into their neighbours, and so forth. This results in a wave of vibrations travelling through the air to the eardrum, which in turn also vibrates.
To solve this problem it is necessary to apply the concepts related to the relationship between tangential velocity and centripetal velocity, as well as the kinematic equations of angular motion. By definition we know that the direction of centripetal acceleration is perpendicular to the direction of tangential velocity, therefore:

Where,
V = the linear speed
r = Radius
Angular speed
The angular speed is given by


Replacing at our first equation we have that the centripetal acceleration would be



To transform it into multiples of the earth's gravity which is given as
the equivalent of 1g.


PART B) Now the linear speed would be subject to:



Therefore the linear speed of a point on its edge is 51.05m/s
A = <0,1>
B = <-1,3>
then
A + B = < 0+-1 , 1+3 > = <-1, 4>
magnitude = sqrt( (-1)^2 + (4)^2 )
= sqrt( 1 + 16)
= sqrt(17)