91Ó°ÊÓ

Estimate the maximum possible sound level in decibels of sound waves in air. (Hint: Set the pressure amplitude equal to \(1 \mathrm{~atm} .\) )

Two sources of sound are separated by a distance of \(5.00 \mathrm{~m}\). They both emit sound at the same amplitude and frequency,\(300 \mathrm{~Hz}\), but they are \(180^{\circ}\) out of phase. At what points along the line connecting them will the sound intensity be the largest?

A sound wave in a fluid medium is reflected at a barrier so that a standing wave is formed. The distance between nodes is \(3.84 \mathrm{~cm}\) and the speed of propagation is \(1520 \mathrm{~m} / \mathrm{s}\). Find the frequency.

The A string of a violin is a little too taut. Four beats per second are heard when it is sounded together with a tuning fork that is vibrating accurately at the pitch of concert \(\mathrm{A}(440 \mathrm{~Hz})\). What is the period of the violin string vibration?

The \(15.8-\mathrm{kHz}\) whine of the turbines in the jet engines of an aircraft moving with speed \(193 \mathrm{~m} / \mathrm{s}\) is heard at what frequency by the pilot of a second craft trying to overtake the first at a speed of \(246 \mathrm{~m} / \mathrm{s}\) ?

An ambulance emitting a whine at \(1602 \mathrm{~Hz}\) overtakes and passes a cyclist pedaling a bike at \(2.63 \mathrm{~m} / \mathrm{s}\). After being passed, the cyclist hears a frequency of \(1590 \mathrm{~Hz}\). How fast is the ambulance moving?

A bat is flitting about in a cave, navigating very effectively by the use of ultrasonic bleeps (short emissions of highfrequency sound lasting a millisecond or less and repeated several times a second). Assume that the sound emission frequency of the bat is \(39.2 \mathrm{kHz}\). During one fast swoop directly toward a flat wall surface, the bat is moving at \(8.58 \mathrm{~m} / \mathrm{s}\). Calculate the frequency of the sound the bat hears reflected off the wall.