# Physics

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The water level in a vertical glass tube 1.40 m long can be adjusted to any position in the tube. A tuning fork vibrating at 440 Hz is held just over the open top end of the tube, to set up a standing wave of sound in the air-filled top portion of the tube. (That air-filled top portion acts as a tube with one end closed and the other end open.)
(a) For how many different positions of the water level will sound from the fork set up resonance in the tube's air-filled portion, which acts as a pipe with one end closed (by the water) and the other end open?

(b) What is the least water height in the tube for resonance to occur?

(c) What is the second least water heights in the tube for resonance to occur?

• Physics -

Hi, I got the answer to part A but not B or C...

A) use F=(nV)/(2L)
F=frequency
n=number of nodes
V=speed of sound (usually 343 m/s)
L=length of tube

rearrange the equation to solve for n,
round down to the nearest integer...

in my notes it says the (2L) should actually be (4L), not sure why it worked for me when I used (2L)