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Two sinusoidal waves with identical wavelengths and amplitudes travel in opposite directions along a string with a speed of \(10 \mathrm{~cm} / \mathrm{s}\). If the time interval between instants when the string is flat is \(0.50 \mathrm{~s}\), what is the wavelength of the waves?

Short Answer

Expert verified
The wavelength of the waves is 10 cm.

Step by step solution

01

Understanding the Problem

Two sinusoidal waves of identical wavelengths and amplitudes are traveling in opposite directions on a string. The point at which the waves interfere destructively results in a flat string. The time interval between these occurrences is given as 0.50 seconds. We need to find the wavelength of these waves.
02

Relation between Speed, Wavelength, and Period

The speed of a wave (v) is given by its wavelength (λ) times its frequency (f): \( v = \lambda \cdot f \). We are given that v = 10 cm/s. We can also express frequency in terms of the period (T) as \( f = \frac{1}{T} \), so \( v = \frac{\lambda}{T} \).
03

Time for a Full Cycle

The time interval given, 0.50 s, is the time between destructive interferences when the string is flat. The string goes from flat to flat in half a wavelength, so this time is equal to half a period: \( \frac{T}{2} = 0.50 \) seconds.
04

Finding the Period

Since \( \frac{T}{2} = 0.50 \), we can solve for T: \( T = 2 \times 0.50 = 1.0 \) second. This is the period of the wave.
05

Calculate the Wavelength

With the wave's speed and period known, use the equation \( v = \frac{\lambda}{T} \) to find the wavelength: \[ \lambda = v \times T = 10 \ \text{cm/s} \times 1.0 \ \text{s} = 10 \ \text{cm}. \]
06

Conclusion

Thus, the wavelength of the sinusoidal waves is 10 cm.

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Key Concepts

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

Sinusoidal Waves
Sinusoidal waves are a fundamental type of wave commonly found in physics. They are named for their waveforms, which resemble the sine function often used in mathematics. Understanding sinusoidal waves is crucial because they frequently occur in diverse fields such as acoustics, optics, and electromagnetism.

These waves are characterized by evenly spaced crests and troughs, and their shape is a smooth, periodic oscillation. The mathematical representation of a sinusoidal wave is described by the equation \( y(x, t) = A \sin(kx - \omega t + \phi) \). Here, \( A \) represents the amplitude, \( k \) the wave number, \( \omega \) the angular frequency, and \( \phi \) the phase.

Key properties of sinusoidal waves include:
  • Amplitude \( (A) \): The maximum extent of oscillation, indicating the wave's strength or intensity.
  • Frequency \( (f) \): The number of oscillations per unit time, related to the period.
  • Period \( (T) \): The duration for one full cycle of the wave.
Understanding these properties allows us to describe how sinusoidal waves travel and interact with their surroundings.
Wavelength Calculation
The wavelength of a wave is the distance between two corresponding points on consecutive cycles, such as crest-to-crest or trough-to-trough. Calculating the wavelength is crucial for understanding wave behavior, particularly in systems experiencing interference.

The relationship between speed, frequency, and wavelength is given by the formula \( v = \lambda \cdot f \), where \( v \) is the wave speed, \( \lambda \) the wavelength, and \( f \) the frequency. To reframe this formula for wavelength calculation, we use \( \lambda = \frac{v}{f} \).

In the context of the problem, we are working with a wave speed of 10 cm/s and need to determine the period from the time interval between destructive interference, which was given as 0.50 seconds. Since this time interval represents half a cycle for destructive interference, the period is calculated as 1 second.
  • Using the formula \( \lambda = v \cdot T \), where \( T \) is the period:
\[ \lambda = 10 \ \text{cm/s} \times 1 \ \text{s} = 10 \ \text{cm} \] Thus, understanding the step-by-step process of identifying wave speed and period makes wavelength calculation straightforward.
Destructive Interference
Destructive interference occurs when two waves superimpose to create a resultant wave with reduced or nullified amplitude. This happens when the crests of one wave align with the troughs of another, leading to "cancellation." In physical terms, if the two waves have equal amplitudes, they can perfectly cancel out at specific points.

Consider the wave problem we've been discussing. The two sinusoidal waves have the same wavelength and amplitude but travel in opposite directions. At specific points along the string, their interaction results in a flat string, a clear indication of destructive interference. The given time interval of 0.50 seconds indicates the time it takes for the waves to move from one point of destructive interference to the next, meaning the string is alternately flat at these intervals.

Significant aspects of destructive interference include:
  • If the waves are perfectly in phase, they constructively interfere, showing heightened amplitude.
  • When they are in opposite phases, they destructively interfere, often resulting in a flat, or node, in the medium.
  • The pattern of destructive interference helps in calculating wavelength and other wave properties.
Recognizing the effects of interference aids in comprehending wave patterns and behaviors in various physical systems.

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Most popular questions from this chapter

If a transmission line in a cold climate collects ice, the increased diameter tends to cause vortex formation in a passing wind. The air pressure variations in the vortexes tend to cause the line to oscillate (gallop), especially if the frequency of the variations matches a resonant frequency of the line. In long lines, the resonant frequencies are so close that almost any wind speed can set up a resonant mode vigorous enough to pull down support towers or cause the line to short out with an adjacent line. If a transmission line has a length of \(347 \mathrm{~m}\), a linear density of \(3.35 \mathrm{~kg} / \mathrm{m},\) and a tension of \(65.2 \mathrm{MN},\) what are (a) the frequency of the fundamental mode and (b) the frequency difference between successive modes?

A sinusoidal transverse wave of amplitude \(y_{m}\) and wavelength \(\lambda\) travels on a stretched cord. (a) Find the ratio of the maximum particle speed (the speed with which a single particle in the cord moves transverse to the wave) to the wave speed. (b) Does this ratio depend on the material of which the cord is made?

Two identical traveling waves, moving in the same direction, are out of phase by \(\pi / 2\) rad. What is the amplitude of the resultant wave in terms of the common amplitude \(y_{m}\) of the two combining waves?

(a) What is the fastest transverse wave that can be sent along a steel wire? For safety reasons, the maximum tensile stress to which steel wires should be subjected is \(7,00 \times 10^{8} \mathrm{~N} / \mathrm{m}^{2}\). The density of steel is \(7800 \mathrm{~kg} / \mathrm{m}^{3}\). (b) Does your answer depend on the diameter of the wire?

What is the speed of a transverse wave in a rope of length \(2.00 \mathrm{~m}\) and mass \(60.0 \mathrm{~g}\) under a tension of \(500 \mathrm{~N} ?\)

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