Answer:
67.31 Hz, 201.92 Hz, 336.54 Hz
Explanation:
Resonance also known as standing wave occur when a uniform tube is closed at one end and open at the other end.
For a resonance wave in a tube with length b, wavelength λ of resonance wave is 4b because a quarter wave is formed in the tube, that is,
λ = 4b.
When the speed of sound is c, the frequency of sound, f, is
f = c /λ,
and therefore,
f = c / ( 4b ).
From the question,
When c = 350 m/s and b = 1.3 m,
using the formula
fn = c / ( 4b ) × n (n = 1, 3, 5, ...).
The first three resonant frequencies are;
First resonance frequency is
f = 350 / (4*1.3) * 1 = 67.31 Hz
Second resonance frequency is
f = 350 / (4*1.3) * 3 = 201.92 Hz
Third resonance frequency is
f = 350 / (4*1.3) * 5 = 336.54 Hz
