Prong of a vibrating tuning fork is in contact with water surface. It produces concentric circular waves on the surface of water. The distance between five consecutive crests is 0.8 m and the velocity of wave on the water surface is $56 \mathrm{~m} / \mathrm{s}$. The frequency of tuning fork is

The end correction for the vibrations of air column in a tube of circular cross-section will be more if the tube is

Stationary wave is produced along the stretched string of length 80 cm . The resonant frequencies of string are $90 \mathrm{~Hz}, 150 \mathrm{~Hz}$ and 210 Hz . The speed of transverse wave in the string is

The pipe open at both ends and pipe closed at one end have same length and both are vibrating in fundamental mode. Air column vibrating in open pipe has resonance frequency $n_1$ and air column vibrating in closed pipe has resonance frequency $\mathrm{n}_2$, then