Related InterviewSolutions

• Two trains are traveling towards each other both at a speed of 90 km/h. If one of the trains sounds a whistle at 500 Hz, what will be the apparent frequency heard in the other train? The speed of sound in air = 350 m/s.
• A traffic policeman sounds a whistle to stop a car-driver approaching towards him. The car driver does not stop and takes the plea in court that because of the Doppler shift the frequency of the whistle reaching him might have gone beyond the audible limit of 20 kHz and he did not hear it. Experiments showed that the whistle emits a sound with a frequency close to 16 kHz. Assuming that the claim of the driver is true, how fast was he driving the car? Take the speed of sound in air to be 330 m/s. Is this speed practical with today's technology?
• The engine of a train sounds a whistle at frequency v. The frequency heard by a passenger is(a) > v(b) < v(c) =1/v(d) = v.
• Figure shows a source of sound moving along the X-axis at a speed of 22 m/s continuously emitting a sound of frequency 2.0 kHz which travels in air at a speed of 330 m/s. A listener Q stands on the Y-axis at a distance of 330 m from the origin. At t = 0, the source crosses the origin P. (a) When does the sound emitted from the source at P reach the listener at Q? (b) What will be the frequency heard by the listener at this instant? (c) Where will the source be at this instant?
• In a standing wave pattern in a vibrating air column, nodes are formed at a distance of 4.0 cm. If the speed of sound in air is 328 m/s, what is the frequency of the source?
• A cylindrical metal tube has a length of 50 cm and is open at both ends. Find the frequencies between 1000 Hz and 2000 Hz at which the air column in the tube can resonate. The speed of sound in air is 340 m/s. 
• The separation between a node and the next antinode in a vibrating air column is 25 cm. If the speed of sound in air is 340 m/s, find the frequency of vibration of the air column.
• Two loudspeakers are arranged facing each other at some distance. Will a person standing behind one of the loudspeakers clearly hear the sound of the other loudspeaker or the clarity will be seriously damaged because of the "collision" of the two sounds in between? 
• Two submarines are approaching each other in a calm sea. The first submarine travels at a speed of 36 km/h and the other at 54 km/h relative to the water. The first submarine sends a sound signal (sound waves in water are also called sonar) at a frequency of 2000 Hz. (a) At what frequency is the signal received by the second submarine? (b) The signal is reflected from the second submarine. At what frequency is this signal received by the first submarine. Take the speed of the sound wave in water to be 1500 m/s.
• A small source of sound moves on a circle as shown-in figure (16-Q1) and an observer is sitting at o. Let v1, v2, v3 be the frequencies heard when the sours.e-is-at A, B and C respectively.(a) v1&gt;v2&gt;v3(b) v1 = v2 &gt; v3(c) v2 &gt; v3 &gt; v1(d) v1 &gt; v2 &gt; v2.