Question

Two tuning forks when sounded together produce $6$ beats/s. The first fork has the frequency $3$% higher than a standard one and the second has the frequency $2$% less than the standard fork. The frequencies for the forks are

• A. $126.3,120.3Hz$
• B. $162.7,156.7Hz$
• C. $136.2,130.2Hz$
• D. $123.6,117.6Hz$

Answer 1

The correct option is D $123.6,117.6Hz$

$\left(f+\frac{3f}{100}\right)-\left(f-\frac{2f}{100}\right)=6$

$\Rightarrow 5f=600$

or

$f=120Hz$

$f+\frac{3f}{100}=123.6$Hz,
$f-\frac{2f}{100}=120-\frac{2\times 120}{100}=117.6$Hz,