/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 35 A string of length \(L\) vibrate... [FREE SOLUTION] | 91Ó°ÊÓ

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A string of length \(L\) vibrates at its fundamental frequency. The amplitude at a point \(\frac{1}{4} L\) from one end is \(2.0 \mathrm{cm} .\) What is the amplitude of each of the traveling waves that form this standing wave?

Short Answer

Expert verified
The amplitude of each of the traveling waves that form the standing wave is \(1.0 \mathrm{cm}\).

Step by step solution

01

Understanding the concept of standing waves

A standing wave is the result of the superposition of two waves of the same frequency and magnitude traveling in opposite directions. The resulting wave appears to stand in place, hence the name standing wave. The points of maximum displacement, known as antinodes, occur where the two waves add constructively. The amplitude of the standing wave is twice the amplitude of the original waves.
02

Identifying given variables

In this exercise, we're told that the amplitude at a point \(\frac{1}{4} L\) from one end is \(2.0 \mathrm{cm}\). This is the amplitude of the standing wave.
03

Calculating the amplitude of each travelling wave

Since a standing wave's amplitude is twice the amplitude of each of the traveling waves that form it, we can find the amplitude of each traveling wave by dividing the given amplitude of the standing wave by 2. Thus, the amplitude of each traveling wave is \(\frac{2.0 \mathrm{cm}}{2} = 1.0 \mathrm{cm}\)

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Amplitude
In the context of waves, the amplitude is a measure of the wave's maximum displacement from its equilibrium or rest position. For a standing wave, which arises when two waves of the same frequency and magnitude travel in opposite directions, the amplitude can be visualized in the regions of maximum displacement called antinodes. The amplitude tells us how intense the wave is at its peak points.

  • The amplitude of a traveling wave is the height from the middle of the wave to its peak.
  • A larger amplitude means a stronger or more intense wave.
  • The amplitude is always a positive value but may vary in measurement units such as centimeters or meters depending on the wave's size.

In our exercise, we are given the amplitude of the standing wave at a specific point as 2.0 cm. To find the amplitude of each traveling wave that contributes to forming the standing wave, we must consider that the standing wave amplitude is twice that of each individual traveling wave. Hence, each traveling wave has an amplitude of 1.0 cm. This relation helps us understand how the waves interact when they overlap.
Fundamental Frequency
The fundamental frequency is the lowest frequency at which a system vibrates. This frequency is critical because it determines the basic mode of vibration for a given string or medium. Standing waves on strings and other mediums mostly vibrate at this frequency since it's the simplest mode.

  • The fundamental frequency is related to several factors such as the length of the medium (e.g., a string), its tension, and its mass density.
  • A mode of vibration, which corresponds to the fundamental frequency, is often the most prominent vibration pattern.
  • Higher harmonics are multiples of the fundamental frequency, known as overtones.

In our situation, the string vibrating at its fundamental frequency tells us that the resultant wave pattern is the simplest and most basic mode the string can achieve. Recognizing this allows us to simplify certain calculations, like deducing wave behavior at specific points on the string, such as \(\frac{1}{4} L\). This understanding helps in solving for the amplitude across the standing wave.
Superposition of Waves
The principle of superposition is a fundamental concept in wave mechanics. It explains how waves can overlap and combine to form new wave patterns. For standing waves specifically, this principle is beautifully illustrated. When two waves traveling in opposite directions meet, they superimpose upon each other.

  • When waves meet, they can add constructively, creating places of greater displacement known as antinodes.
  • Alternatively, they can interfere destructively, leading to points of zero displacement known as nodes.
  • Superposition is key to understanding phenomena like standing waves and how they are visually distinctive.

In our problem, this superposition results in the amplitude of the standing wave being double that of the individual traveling waves. By applying superposition, we can see how the amplitude at antinodes becomes a sum of the contributions from each wave in motion. This process is central to visualizing how standing waves are formed and behave on a vibrating string.

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Most popular questions from this chapter

If \(A\) 25-cm-long wire with a linear density of \(20 \mathrm{g} / \mathrm{m}\) passes across the open end of an \(85-\) cm-long open-closed tube of air. If the wire, which is fixed at both ends, vibrates at its fundamental frequency, the sound wave it generates excites the second vibrational mode of the tube of air. What is the tension in the wire? Assume \(v_{\text {sound }}=340 \mathrm{m} / \mathrm{s}\).

Two loudspeakers face each other from opposite walls of a room. Both are playing exactly the same frequency, thus setting up a standing wave with distance \(\lambda / 2\) between antinodes. Assume that \(\lambda\) is much less than the room width, so there are many antinodes. a. Yvette starts at one speaker and runs toward the other at speed \(v_{Y} .\) As the does so, she hears a loud-soft-loud modulation of the sound intensity. From your perspective, as you sit at rest in the room, Yvette is running through the nodes and antinodes of the standing wave. Find an expression for the number of sound maxima she hears per second. b. From Yvette's perspective, the two sound waves are Doppler shifted. They're not the same frequency, so they don't create a standing wave. Instead, she hears a loud-soft-loud modulation of the sound intensity because of beats. Find an expression for the beat frequency that Yvette hears. c. Are your answers to parts a and b the same or different? Should they be the same or different?

A 121 -cm-long, \(4.0 \mathrm{g}\) string oscillates in its \(m=3\) mode with a frequency of \(180 \mathrm{Hz}\) and a maximum amplitude of \(5.0 \mathrm{mm}\) What are (a) the wavelength and (b) the tension in the string?

a. The frequency of a standing wave on a string is \(f\) when the string's tension is \(T\). If the tension is changed by the small amount \(\Delta T\), without changing the length, show that the frequency changes by an amount \(\Delta f\) such that 1 $$ \frac{\Delta f}{f}=\frac{1}{2} \frac{\Delta T}{T} $$ b. Two identical strings vibrate at \(500 \mathrm{Hz}\) when stretched with the same tension. What percentage increase in the tension of one of the strings will cause five beats per second when both strings vibrate simultancously?

A \(1.0-\) m-tall vertical tube is filled with \(20^{\circ} \mathrm{C}\) water. A tuning fork vibrating at \(580 \mathrm{Hz}\) is held just over the top of the tube as the water is slowly drained from the bottom. At what water heights, measured from the bottom of the tube, will there be a standing wave in the tube above the water?

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