Two waves of lengths $50 \; cm$ and $51 \; cm$ produce $12$ beats per second. The velocity of sound is .... $m/s$.

$A$ tuning fork arrangement (pair) produces $4 \, beats/sec$ with one fork of frequency $288 \, cps$. $A$ little wax is placed on the unknown fork and it then produces $2 \, beats/sec$. The frequency of the unknown fork is .... $cps$.

The sound waves of wavelengths $5 \,m$ and $6 \,m$ produce $30$ beats in $3 \,s$. The velocity of sound is (in $\,m/s$)

Two strings $A$ and $B$ produce beats of frequency $\Delta f_1 > 0$. The tension in string $A$ is slightly increased and the beat frequency is found to be $\Delta f_2 > 0$. If the original frequency of $A$ is $f_0$ and $\Delta f_2 < \Delta f_1$, then the frequency of $B$ is

An unknown frequency $x$ produces $8$ beats per second with a frequency of $250 \ Hz$ and $12$ beats per second with a $270 \ Hz$ source. Then $x$ is .... $Hz$.

Two adjacent piano keys are struck simultaneously. The notes emitted by them have frequencies $n_1$ and $n_2$. The number of beats heard per second is