An observer is riding on a bicycle and moving towards a hill at 18 kmh^-1. He hears a sound from a source at some distance behind him directly as well as after its reflection from the hill. If the original frequency of the sound as emitted by source is 640 Hz and velocity of the sound in air is 320 m/s, the beat frequency between the two sounds heard by observer will be _________ Hz.

A set of 16 tuning forks are so arranged that each produce 4 beats with the previous one. If the frequency of last tuning fork is double that of first, the frequency of third tuning fork is

A pipe open at both ends produces a note of fundamental frequency V₁. When the pipe is kept with (1/3)^rd of its length in water, it produces a note of frequency V₂.The value of V₁/ V₂ is

A string of linear density 0.4 kg/m is stretched with force of 1000 N. A transverse wave is set up along it. The speed of the wave is

A particle is executing S.H.M. its potential energy v/s displacement graph is given by

The value of restoring force constant is :-

A heavy rope is suspended from rigid support. A wave pulse is set up at the lower end. Then