A) As a wind instrument warms up, the resonant frequencies of the instrument tend to slightly decrease.
B) If the air in a concert hall warms up, the resonant frequencies of the string instruments will change precisely the same as the resonant frequencies of the wind instruments.
C) If you pluck a string one third of the way along its length, you tend to suppress the third harmonic (n=3).
D) If the slide of a trombone is pushed outwards (making the effective tube length longer), all the resonant frequencies of the instrument increase.
I thought the answer was TTFF, but it was wrong. Any idea?
To determine the correct answer, let's analyze each statement one by one:
A) As a wind instrument warms up, the resonant frequencies of the instrument tend to slightly decrease.
Explanation: When a wind instrument warms up, the air molecules inside the instrument gain energy and move more quickly. This increased molecular motion causes the speed of sound in the instrument to increase. Since the speed of sound is directly proportional to the frequency of sound waves, an increase in speed of sound will result in a higher resonant frequency rather than a decrease. Therefore, statement A is incorrect.
B) If the air in a concert hall warms up, the resonant frequencies of the string instruments will change precisely the same as the resonant frequencies of the wind instruments.
Explanation: The resonant frequencies of wind instruments and string instruments are determined by different factors. Wind instruments rely on the length, shape, and opening of the instrument, while string instruments depend on the tension, length, and thickness of the string. Therefore, the resonant frequencies of wind and string instruments do not change precisely the same way when the air in a concert hall warms up. Consequently, statement B is incorrect.
C) If you pluck a string one third of the way along its length, you tend to suppress the third harmonic (n=3).
Explanation: The harmonic series on a string corresponds to integer multiples of the fundamental frequency. The third harmonic (n=3) is an important component in the harmonic series. When you pluck a string one third of the way along its length, you actually enhance the third harmonic rather than suppress it. Therefore, statement C is incorrect.
D) If the slide of a trombone is pushed outwards (making the effective tube length longer), all the resonant frequencies of the instrument increase.
Explanation: In a trombone, changing the effective tube length alters the resonant frequencies. When the slide is pushed outwards, the length of the vibrating air column inside the trombone increases, resulting in longer wavelengths and lower frequencies. Therefore, statement D is incorrect.
Based on the explanations provided, the correct answer is FFTF.