A wire having length \(\mathrm{L}\) is kept under tension between \(\mathrm{x}=0\) and \(\mathrm{x}=\mathrm{L}\). In one experiment, the equation of the wave and energy is given by $\mathrm{y}_{1}=\mathrm{A} \sin (\pi \mathrm{x} / \mathrm{L}) \sin \omega \mathrm{t}\( and \)\mathrm{E}_{1}$ respectively. In another experiment, it is \(\mathrm{y}_{2}=\mathrm{A} \sin\) \(\\{(2 \pi \mathrm{x}) / \mathrm{L}\\} \sin 2 \omega \mathrm{t}\) and \(\mathrm{E}_{2}\). Then........ (A) \(E_{2}=E_{1}\) (B) \(E_{2}=2 \mathrm{E}_{1}\) (C) \(\mathrm{E}_{2}=4 \mathrm{E}_{1}\) (D) \(E_{2}=16 \mathrm{E}_{1}\)

Short Answer

Expert verified
The correct answer is (C) \(E_2 = 4E_1\).

Step by step solution

01

Calculate energy expression for the first wave

We are given the wave equation for the first experiment as: \(y_1 = A \sin(\frac{\pi x}{L}) \sin(\omega t)\) To find the energy expression for this wave, we know that the wave energy can be expressed as: \(E = \frac{1}{2} \mu \int_0^L (\frac{\partial y}{\partial t})^2 dx\) First, we need to find the time derivative of the wave equation: \(\frac{\partial y_1}{\partial t} = A \sin(\frac{\pi x}{L}) \cos(\omega t) \cdot \omega\) Now, we will square the time derivative: \((\frac{\partial y_1}{\partial t})^2 = \omega^2 A^2 \sin^2(\frac{\pi x}{L})\cos^2(\omega t)\) Now we can find the energy expression for the first experiment by plugging this value into the energy expression formula: \(E_1 = \frac{1}{2} \mu \int_0^L \omega^2 A^2 \sin^2(\frac{\pi x}{L})\cos^2(\omega t) dx\)
02

Calculate energy expression for the second wave

We are given the wave equation for the second experiment as: \(y_2 = A \sin(\frac{2 \pi x}{L}) \sin(2\omega t)\) Now, similar to the first wave, we will find the time derivative of the wave equation: \(\frac{\partial y_2}{\partial t} = A \sin(\frac{2 \pi x}{L}) \cos(2\omega t) \cdot 2\omega\) Then we square the time derivative: \((\frac{\partial y_2}{\partial t})^2 = 4\omega^2 A^2 \sin^2(\frac{2\pi x}{L})\cos^2(2\omega t)\) Now we can find the energy expression for the second experiment: \(E_2 = \frac{1}{2} \mu \int_0^L 4\omega^2 A^2 \sin^2(\frac{2\pi x}{L})\cos^2(2\omega t) dx\)
03

Compare energy expressions of both waves to find the relationship

Now we have the energy expressions for both the first and second experiments: \(E_1 = \frac{1}{2} \mu \int_0^L \omega^2 A^2 \sin^2(\frac{\pi x}{L})\cos^2(\omega t) dx\) \(E_2 = \frac{1}{2} \mu \int_0^L 4\omega^2 A^2 \sin^2(\frac{2\pi x}{L})\cos^2(2\omega t) dx\) We can see that the only difference between these two expressions are the coefficients of \(\omega^2 A^2\) in the integral: First integral has \(\omega^2 A^2\), while the second integral has \(4\omega^2 A^2\). Therefore, the energy expressions are related to each other as: \(E_2 = 4E_1\) Thus, the correct answer is: (C) \(E_2=4E_1\)

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

When the displacement of a S.H.O. is equal to \(\mathrm{A} / 2\), what fraction of total energy will be equal to kinetic energy ? \\{A is amplitude \(\\}\) (A) \(2 / 7\) (B) \(3 / 4\) (C) \(2 / 9\) (D) \(5 / 7\)

A block having mass \(\mathrm{M}\) is placed on a horizontal frictionless surface. This mass is attached to one end of a spring having force constant \(\mathrm{k}\). The other end of the spring is attached to a rigid wall. This system consisting of spring and mass \(\mathrm{M}\) is executing SHM with amplitude \(\mathrm{A}\) and frequency \(\mathrm{f}\). When the block is passing through the mid-point of its path of motion, a body of mass \(\mathrm{m}\) is placed on top of it, as a result of which its amplitude and frequency changes to \(\mathrm{A}^{\prime}\) and \(\mathrm{f}\). The ratio of amplitudes $\left(\mathrm{A}^{1} / \mathrm{A}\right)=\ldots \ldots \ldots$ (A) \(\sqrt{\\{}(\mathrm{M}+\mathrm{m}) / \mathrm{m}\\}\) (B) \(\sqrt{\\{m} /(\mathrm{M}+\mathrm{m})\\}\) (C) \(\sqrt{\\{} \mathrm{M} /(\mathrm{M}+\mathrm{m})\\}\) (D) \(\sqrt{\\{}(\mathrm{M}+\mathrm{m}) / \mathrm{M}\\}\)

A block having mass \(\mathrm{M}\) is placed on a horizontal frictionless surface. This mass is attached to one end of a spring having force constant \(\mathrm{k}\). The other end of the spring is attached to a rigid wall. This system consisting of spring and mass \(\mathrm{M}\) is executing SHM with amplitude \(\mathrm{A}\) and frequency \(\mathrm{f}\). When the block is passing through the mid-point of its path of motion, a body of mass \(\mathrm{m}\) is placed on top of it, as a result of which its amplitude and frequency changes to \(\mathrm{A}^{\prime}\) and \(\mathrm{f}\). The ratio of frequencies \((\mathrm{f} / \mathrm{f})=\ldots \ldots \ldots\) (A) \(\sqrt{\\{} \mathrm{M} /(\mathrm{m}+\mathrm{M})\\}\) (B) \(\sqrt{\\{\mathrm{m} /(\mathrm{m}+\mathrm{M})\\}}\) (C) \(\sqrt{\\{\mathrm{MA} / \mathrm{mA}}\\}\) (D) \(\sqrt{[}\\{(\mathrm{M}+\mathrm{m}) \mathrm{A}\\} / \mathrm{mA}]\)

Length of a steel wire is \(11 \mathrm{~m}\) and its mass is \(2.2 \mathrm{~kg}\). What should be the tension in the wire so that the speed of a transverse wave in it is equal to the speed of sound in dry air at \(20^{\circ} \mathrm{C}\) temperature? (A) \(2.31 \times 10^{4} \mathrm{~N}\) (B) \(2.25 \times 10^{4} \mathrm{~N}\) (C) \(2.06 \times 10^{4} \mathrm{~N}\) (D) \(2.56 \times 10^{4} \mathrm{~N}\)

A wave \(\mathrm{y}=\mathrm{a} \sin (\omega \mathrm{t}-\mathrm{kx})\) on a string meets with another wave producing a node at \(\mathrm{x}=0 .\) Then the equation of the unknown wave is \(\ldots \ldots \ldots\) (A) \(y=a \sin (\omega t+k x)\) (B) \(\mathrm{y}=-\mathrm{a} \sin (\omega \mathrm{t}+\mathrm{kx})\) (C) \(\mathrm{y}=\mathrm{a} \sin (\omega \mathrm{t}-\mathrm{kx})\) (D) \(\mathrm{y}=-\mathrm{a} \sin (\omega \mathrm{t}-\mathrm{kx})\)

See all solutions

Recommended explanations on English Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free