$A$ light pointer fixed to one prong of a tuning fork touches a vertical plate. The fork is set vibrating and the plate is allowed to fall freely. If eight oscillations are counted when the plate falls through $10 \, cm$,the frequency of the tuning fork is .... $Hz$

Beats are the result of

Two sitar strings,$A$ and $B$,playing the note $'Dha'$ are slightly out of tune and produce beats at a frequency of $5 \, Hz$. The tension of string $B$ is slightly increased and the beat frequency is found to decrease to $3 \, Hz$. If the frequency of $A$ is $425 \, Hz$,the original frequency of $B$ is ... $Hz$.

Two strings $X$ and $Y$ of a sitar produce a beat frequency of $4 \ Hz$. When the tension of the string $Y$ is slightly increased,the beat frequency is found to be $2 \ Hz$. If the frequency of $X$ is $300 \ Hz$,then the original frequency of $Y$ was .... $Hz$.

Why don't we experience beats in case of superposition of two sound waves with a large difference in their frequencies?

The wavelengths of two sound notes in air are $\frac{40}{195} \,m$ and $\frac{40}{193} \,m$. Each note produces $9$ beats per second separately with a third note of fixed frequency. The velocity of sound in air in $m/s$ is