Q.15.27 A bat is flitting about in a cave, navigating via ultrasonic beeps. Assume that the sound emission frequency of the bat is . During one fast swoop directly toward a flat wall surface, the bat is moving at 0.03 times the speed of sound in air. What frequency does the bat hear reflected off the wall ?
Q.15.26 Earthquakes generate sound waves inside the earth. Unlike a gas, the earth can experience both transverse (S) and longitudinal (P) sound waves. Typically the speed of S wave is about , and that of P wave is . A seismograph records P and S waves from an earthquake. The first P wave arrives 4 min before the first S wave. Assuming the waves travel in straight line, at what distance does the earthquake occur?
Q.15.25 A SONAR system fixed in a submarine operates at a frequency . An enemy submarine moves towards the SONAR with a speed of . What is the frequency of sound reflected by the submarine? Take the speed of sound in water to be .
Q.15.24 One end of a long string of linear mass density is connected to an electrically driven tuning fork of frequency . The other end passes over a pulley and is tied to a pan containing a mass of . The pulley end absorbs all the incoming energy so that reflected waves at this end have negligible amplitude. At , the left end (fork end) of the string has zero transverse displacement and is moving along positive y-direction. The amplitude of the wave is . Write down the transverse displacement y as function of x and t that describes the wave on the string.
Q.15.23 A narrow sound pulse (for example, a short pip by a whistle) is sent across a medium. (a) Does the pulse have a definite (i) frequency, (ii) wavelength, (iii) speed of propagation? (b) If the pulse rate is 1 after every , (that is the whistle is blown for a split of second after every ), is the frequency of the note produced by the whistle equal to or ?
Q.15.22 A travelling harmonic wave on a string is described by
(b) Locate the points of the string which have the same transverse displacements and velocity as the point at 5 s and 11 s.
Q.15.22 (a) A travelling harmonic wave on a string is described by
(a) what are the displacement and velocity of oscillation of a point at , and ? Is this velocity equal to the velocity of wave propagation?