Waves - Mechanics - Physics Previous Year Questions

A person is standing at some point between two parallel cliffs (not exactly at the centre). He claps, and hears two echoes: the first after \(1 \mathrm{~s}\) and the second after \(2 \mathrm{~s}\). If the speed of sound in air is \(330 \mathrm{~m} / \mathrm{s}\), the distance between the two cliffs is

The frequency of a sonometer wire is \(100 \mathrm{~Hz}\) When the weights producing the tensions are completely immersed in water, the frequence becomes \(60 \mathrm{~Hz}\) and on immersing the weights in a certain liquid, the frequency becomes \(40 \mathrm{~Hz}\). The specific gravity of the liquid is

In the equation for a stationary wave given by $y=5 \cos \frac{\pi x}{25} \sin 100 \pi t$. Here, $x$ is in cm and $t$ in second. A node will not occur at distance $x$ is equal to