The speed of sound in oxygen $(O_2)$ at a certain temperature is $460\, ms^{-1}$. The speed of sound in helium $(He)$ at the same temperature will be ............. $\mathrm{m/s}$  (assume both gases to be ideal)

A string of mass $2.5\, kg$ under some tension. The length of the stretched string is $20\, m$. If the transverse jerk produced at one end of the string takes $0.5\, s$ to reach the  other end, tension in the string is .... $N$

A set of $24$ tunning fork is arranged in a series of increasing frequencies. If each fork gives $4\, beats/second$ with the preceeding one and frequency of last tunning fork is two times of first fork. Find frequency of $5^{th}$ tunning fork  .... $Hz$

The pattern of standing waves formed on a stretched string at two instants of time (extreme, mean) are shown in figure. The velocity of two waves superimposing to form stationary waves is $360\, ms^{-1}$ and their frequencies are $256\, Hz$. Which is not possible value of $t$ (in $\sec$) :-

Two identical flutes produce fundamental notes of frequency $300\,Hz$ at $27\,^oC$. If the temperature of air in one flute is increased to $31\,^oC$, the number of the beats heard per second will be

Two tuning forks $A$ and $B$ produce $8\, beats/s$ when sounded together. $A$ gas column $37.5\, cm$ long in a pipe closed at one end resonate to its fundamental mode  with fork $A$ whereas a column of length $38.5 \, cm$ of the same gas in a similar pipe  is required for resonance with fork $B$. The frequencies of these two tuning forks, are