Two tuning forks A and B produce 8 beats per second. The sum of their original frequencies is 702 Hz. Fork A is filed, increasing its frequency, and the beat frequency decreases. If the original frequency of fork A is N Hz, find N.
Physics · Wave Motion · beat and properties of sound
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Question

Two tuning forks A and B produce 8 beats per second. The sum of their original frequencies is 702 Hz. Fork A is filed, increasing its frequency, and the beat frequency decreases. If the original frequency of fork A is N Hz, find N.

Physics · Wave Motion · beat and properties of sound

G1 Physics · Accepted Answer

Let the original frequencies be f₁ and f₂. Given, |f₁−f₂| = 8 and f₁+f₂ = 702. The two possible frequencies are (702−8)/2 = 347 Hz and (702+8)/2 = 355 Hz. Filing A increases its frequency and the beat frequency decreases. Therefore A must originally be the lower-frequency fork. Hence, f₁ = 347 Hz. Thus, N = 347.