Question 189: Waves

Question

A musician using an open flute of length 50 cm producess second harmonic sound waves. A person runs towards the musician from another end of hall at  a speed of 10 km/h. If the wave speed is 330 m/s, the frequency heard by the running person shall be close to :

Accepted Answer

Frequency of sound wave produce by flute
=  $${{2{V_S}} \over {2\ell }}$$
=  $${{2 	imes 330} \over {2 	imes 50 	imes {{10}^{ - 2}}}}$$
= 660 Hz
Speed of the observer
= 10km/hr
= 10 $$ 	imes $$ $${5 \over {18}}$$ m/s
= $${{25} \over 9}$$ m/s
Frequency heard by the observer,
f' = $$\left( {{{{V_S} + {V_o}} \over {{V_S}}}} ight)f$$
=  $$\left( {{{330 + {{25} \over 9}} \over {330}}} ight) 	imes 660$$
= 666 Hz

Answer

666 Hz

Answer

753 Hz

Answer

500 Hz

Answer

333 Hz

Waves

A musician using an open flute of length 50 cm producess second harmonic sound waves. A person runs towards the musician from another end of hall at a speed of 10 km/h. If the wave speed is 330 m/s, the frequency heard by the running person shall be close to :

Choose the correct answer: