Question

In standing waves experiments, a) with a 660Hz tuning fork you measure a distance of 25 +/- 2cm between adjacent nodes. Is the value of c = 340 m/s a value within the uncertainty of your measured value? b) If you blow air along the top of an open soda bottle you can excite a standing wave and hear a sound. Explain what happens if you put some water into the bottle and then perform the same experiment.

Answer 1

(a)

yes the value of c is within in uncertaintiy value we know
V = f lambda
f = 660hz
lamda= 27cm or (25+2) = 0.27m
V=660*0.27*2=356.4 m/s
lamda= 23cm (25-2) = 0.23m
V=660*0.23*2 = 303.6 m/s

Yes our value lies with in 354.6 and 303.6.

So Yes c lies within uncertainity value.

As wavelength is given till one node we multiply it with 2 to get full wavelength ( lamda )

(b) The pitch of the note gets higher as you add more water.

Pitch is just a measure of how fast the vibration is that reaches your ear, rapid vibrations mean high pitches.

In larger bottle there is more space when you add water it becomes less so it takes less time to build up the pressure which will cause vibration in a less time

This means vibration happens more quickly hence producing a higher pitch.