Answer: The third lowest natural frequency of a closed pipe can be calculated using the formula:
f = (2n-1) v / 4L
where:
n = the harmonic number (in this case, 3)
v = the speed of sound in air at the given temperature (30°C)
L = the length of the pipe (88 cm)
The speed of sound in air at 30°C can be calculated using the formula:
v = 331.5 + 0.6T
where T is the temperature in Celsius.
So, v = 331.5 + 0.6(30) = 349.5 m/s
Converting the length of the pipe to meters, we get:
L = 0.88 m
Plugging in the values, we get:
f = (2(3)-1) (349.5 m/s) / 4(0.88 m) = 236.9 Hz
Therefore, the third lowest natural frequency of an 88 cm closed pipe at 30°C is 236.9 Hz.
Step-by-step explanation: