Ch 10.2 Quiz

I also didn't really understand that explanation for number two, so I did it this way...

f''=[(V+Vm)/(V-Vm)]f

The wall is both moving towards you as you are towards it. You can also convince yourself that because f'' is larger than f, you must add Vm on top and subtract Vm on the bottom so that the fraction will be greater than one. Then you just do some algebra and multiply it out. Both ways work...

4 didn't work for me =(

The maximum wave length is already given to you in m. So it is simply v/length.
Do not multiply the length by anything, there is no need to.
answer in neg.

i also tried number 4 a couple of times and it doesnt work for me either. I really don't understand why you multiply the fundamental by 4.

Hey i just figured it out the question already states the longest wavelength and all you need to do is divide the velocity by the longest wavelength ( which is given) so it is simply: f=v/L

Question 2:

You should have two numbers, one ~300, the other ~500. This example uses 303.1 Hz and 557.7 Hz. 343 m/s is the accepted speed.

x = (557.7-303.1)/(557.7 + 303.1) = 0.295771

Then,

v = xV = 0.295771 x 343 = 101.4495 m s^-1