A string is clamed at both the ends and it is vibrating in its $4^{th}$ harmonic. The equation of the stationary wave is $Y =0.3\,sin\,(0.157\,x) \,cos\,(200\pi t)$. The length of the string is ..... $m$ (all quantities are in $SI$ units)

The first overtone of a stretched wire of given length is $320 Hz$. The first harmonic is  .... $Hz$

A string $1\,\,m$ long is drawn by a $300\,\,Hz$ vibrator attached to its end. The string vibrates in $3$ segments. The speed of transverse waves in the string is equal to .... $m/s$

Which order of harmonics is missing or absent in case of stationary sound waves produced in a closed pipe ?

A steel rod $100\,cm$ long is clamped at its middle. The fundamental frequency of longitudinal vibrations of the rod are given to be $2.53\,kHz$. What is the speed of sound in steel ...... $km/sec$

Two uniform strings of mass per unit length $\mu$ and $4 \mu$, and length $L$ and $2 L$, respectively, are joined at point $O$, and tied at two fixed ends $P$ and $Q$, as shown in the figure. The strings are under a uniform tension $T$. If we define the frequency $v_0=\frac{1}{2 L} \sqrt{\frac{T}{\mu}}$, which of the following statement($s$) is(are) correct?

$(A)$ With a node at $O$, the minimum frequency of vibration of the composite string is $v_0$

$(B)$ With an antinode at $O$, the minimum frequency of vibration of the composite string is $2 v_0$

$(C)$ When the composite string vibrates at the minimum frequency with a node at $O$, it has $6$ nodes, including the end nodes

$(D)$ No vibrational mode with an antinode at $O$ is possible for the composite string