A closed pipe and an open pipe have their first overtone equal in frequency. Then, the lengths of these pipe are in the ratio

In resonance tube, first and second resonance are obtained at depths $$22.7 \mathrm{~cm}$$ and $$70.2 \mathrm{~cm}$$ respectively. The third resonance will be obtained at a depth

A uniform wire $$20 \mathrm{~m}$$ long and weighing $$50 \mathrm{~N}$$ hangs vertically. The speed of the wave at mid point of the wire is (acceleration due to gravity $$=\mathrm{g}=10 \mathrm{~ms}^{-2}$$ )

A passenger is sitting in a train which is moving fast. The engine of the train blows a whistle of frequency '$$n$$'. If the apparent frequency of sound heard by the passenger is '$$f$$' then