A bicycle gear wheel is a disc with 50 ‘teeth' equally spaced around its edge, as shown. The gear wheel is rotated 10 times each second. A springy strip of metal is vibrated by the rotating ‘teeth'. The metal strip produces a sound of frequency that is equal to the frequency of vibration of the strip

Explanation:

The question is not complete, here is the complete question, also see attached the image.

"A bicycle gear wheel is a disc with 50 ‘teeth’ equally spaced around its edge, as shown. The gear  wheel is rotated 10 times each second. A springy strip of metal is vibrated by the rotating ‘teeth’.  The metal strip produces a sound of frequency that is equal to the frequency of vibration of the  strip. The speed of sound in air is 330ms–1.  What is the wavelength of the emitted sound?"

given data

number of teeth= 50        

we are told that the gear is rotated 10 times in 1 sec,  

hence the frequency of the rotation past the strip is

=50*10  

=500Hz    

speed of sound= 330m/s

we know that

  -----------1

where Vw is the speed of sound,

f is its frequency, and

λ is its wavelength.

λ=Vw/f

λ=330/500

λ=0.66m

option number c is the right answer.