Exam 18: Superposition and Standing Waves

A microphone in the ocean is sensitive to the sounds emitted by porpoises. To produce a usable signal, sound waves striking the microphone must have an intensity of 1.02 × 10−¹¹ W/m². If porpoises emit sounds with a power of 0.049 9 W, how far away can a porpoise be and still be heard? Disregard absorption of sound waves by the water.

Two pulses are traveling towards each other at 10 cm/s on a long string at t = 0 s, as shown below. Which diagram below correctly shows the shape of the string at 0.5 s?

An organ pipe open at both ends is 1.5 m long. A second organ pipe that is closed at one end and open at the other is 0.75 m long. The speed of sound in the room is 330 m/s. Which of the following sets of frequencies consists of frequencies which can be produced by both pipes?

Exhibit 18-1 The figure below shows wave crests after a stone is thrown into a pond. Use this exhibit to answer the following question(s). -Refer to Exhibit 18-1. The phase difference in radians between points A and C is

A harmonic longitudinal wave propagating down a tube filled with a compressible gas has the form s(x, t) = s_m cos (kx − ωt). Its velocity can be obtained from

Two harmonic waves traveling in opposite directions interfere to produce a standing wave described by y = 4 sin (5x) cos (6t) where x is in m and t is in s. What is the approximate frequency of the interfering waves?

Two identical strings have the same length and same mass per unit length. String B is stretched with four times as great a tension as that applied to string A. Which statement is correct for all n harmonics on the two strings, n = 1, 2, 3...?

Two waves are described by y₁ = 6 cos 180t and y₂ = 6 cos 186t, (both in meters). What effective frequency does the resultant vibration have at a point?

A fire engine approaches a wall at 5 m/s while the siren emits a tone of 500 Hz frequency. At the time, the speed of sound in air is 340 m/s. How many beats per second do the people on the fire engine hear?

A bat, flying at 5.00 m/s, emits a chirp at 40.0 kHz. If this sound pulse is reflected by a wall, what is the frequency of the echo received by the bat? (v_sound = 340 m/s.)

In a standing wave, not necessarily at the fundamental frequency, on a string of length L, the distance between nodes is

The superposition of two waves, and , results in a wave with a frequency of