This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
The pitch of a sound is related to the frequency of the sound and the source that generates the sound.  It is not directly proportional, but it is directly related in some manner.

As the pitch increases, the voice or sound becomes more shrill. As the pitch decreases the sound becomes coarser.

Let the bicycle move uniformly at v.  Let the radius of the wheel be R.  Let there be N spokes in the wheel.

   f = frequency of the spokes touching the plastic ruler scale
     = N v / (2 π R)

  Every time the spokes touch the scale, the scale vibrates. As the speed of the bicycle decreases, the sound slowly wanes down.

1 5 1