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A string is under tension \(F_{T 1} .\) Energy is transmitted by a wave on the string at rate \(P_{1}\) by a wave of frequency \(f_{1} .\) What is the ratio of the new energy transmission rate \(P_{2}\) to \(P_{1}\) if the tension is doubled?

Short Answer

Expert verified
The ratio of the new energy transmission rate \(P_{2}\) to \(P_{1}\) when the tension is doubled is \(\sqrt{2}\).

Step by step solution

01

Original power transmitted by the wave

Calculate the power transmitted by the wave using the formula \(P = 2\pi^2f^2A^2v\mu\). Since \(f\), \(A\), and \(\mu\) are constants and the velocity of the wave \(v\) is proportional to the square root of the tension (using \(v = \sqrt{\frac{F}{\mu}}\)), we can write this as \(P_{1} = k\sqrt{F_{T1}}\), where \(k\) is a constant that contains the other factors.
02

New power with doubled tension

If the tension is doubled, the new tension is \(F_{T2} = 2F_{T1}\). Calculating the new power \(P_{2}\) after the tension is doubled, we can write \(P_{2} = k\sqrt{F_{T2}} = k\sqrt{2F_{T1}}\).
03

Ratio of new power to original power

The ratio of the new power \(P_{2}\) to the original power \(P_{1}\) can then be written as \(\frac{P_{2}}{P_{1}} = \frac{k\sqrt{2F_{T1}}}{k\sqrt{F_{T1}}} = \sqrt{2}\).

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Key Concepts

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

Wave Velocity
Wave velocity is a fundamental concept in understanding how waves travel through a medium. In the context of a wave on a string, wave velocity (\(v\)) is the speed at which the wave's energy is transmitted along the string. It's important to know that wave velocity depends not just on the wave itself, but also on the physical properties of the string like tension and mass per unit length (\(\mu\)). These properties dictate how quickly and efficiently the wave can travel.

From physics, we have the equation:\[v = \sqrt{\frac{F}{\mu}}\]Here, \(F\) represents the tension in the string, and \(\mu\) is the linear mass density. This equation shows that as the tension in the string increases, the wave velocity also increases. A higher tension means the wave can travel faster because the string is tighter, reducing inertia and allowing the wave to propagate more efficiently.

To put it simply, if you tighten a string, waves will speed up. This process is crucial in musical instruments. Tighter strings on a guitar or violin, for example, produce higher-pitched sounds because the waves travel more quickly.
String Tension
String tension is the pulling force applied along the length of a string. This force significantly impacts how waves behave as they travel along the string. Tension is vital in determining aspects like wave speed and energy transmission. When we speak about string tension in physics or music, we usually discuss forces measured in newtons.

The formula for wave velocity \(v\), \(v = \sqrt{\frac{F}{\mu}}\), highlights the direct relationship between string tension \(F\) and wave velocity. Simply put, increasing the tension in a string increases the velocity at which waves propagate through it. Conversely, reducing tension will slow down the wave velocity.

This concept was clearly seen in the problem solved above. When the tension in the string was doubled, the wave's velocity didn't just slightly increase; it increased proportionately to the square root of the tension increase. This mathematical relationship means that tension adjustments don’t just adjust wave behaviors linearly, which can sometimes counterintuitively result in dramatic effects.
Wave Power Equation
The wave power equation is key to understanding how energy is transmitted through waves. The power \(P\) of a wave can be expressed as:\[P = 2\pi^2f^2A^2v\mu\]Each component of this equation ties into the energy the wave carries. Frequency \(f\), amplitude \(A\), wave velocity \(v\), and mass density \(\mu\) all play a unique role. Higher frequency or amplitude means more energy, translating into more power.

The problem above explores how changes in string tension affect wave power. With tension increasing, wave velocity \(v\) rises, impacting the total power. When tension doubled, \(P_{2}\) was calculated as:\[P_{2} = k\sqrt{2F_{T1}}\]where \(k\) encapsulates constants pertaining to the initial state factors shared by both \(P_{1}\) and \(P_{2}\).

The equation simplifies to show that power \(P\) is directly related to the square root of tension. Ultimately, understanding this relationship helps illustrate why applications like tuning instruments or engineering require careful management of tension to transmit energy efficiently.

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Most popular questions from this chapter

A string of length \(5 \mathrm{m}\) and a mass of \(90 \mathrm{g}\) is held under a tension of 100 N. A wave travels down the string that \(\quad\) is \(\quad\) modeled \(\quad\) as \(y(x, t)=0.01 \mathrm{m} \sin \left(0.40 \mathrm{m}^{-1} x-1170.12 \mathrm{s}^{-1}\right) .\) What is the power over one wavelength?

A sinusoidal wave travels down a taut, horizontal string with a linear mass density of \(\mu=0.060 \mathrm{kg} / \mathrm{m} .\) The magnitude of maximum vertical acceleration of the wave is \(a_{y \max }=0.90 \mathrm{cm} / \mathrm{s}^{2}\) and the amplitude of the wave is \(0.40 \mathrm{m} .\) The string is under a tension of \(F_{T}=600.00 \mathrm{N}\) The wave moves in the negative \(x\) -direction. Write an equation to model the wave.

A wave on a string is driven by a string vibrator, which oscillates at a frequency of \(100.00 \mathrm{Hz}\) and an amplitude of \(1.00 \mathrm{cm} .\) The string vibrator operates at a voltage of \(12.00 \mathrm{V}\) and a current of \(0.20 \mathrm{A}\). The power consumed by the string vibrator is \(P=I V\). Assume that the string vibrator is \(90 \%\) efficient at converting electrical energy into the energy associated with the vibrations of the string. The string is \(3.00 \mathrm{m}\) long, and is under a tension of 60.00 N. What is the linear mass density of the string?

Energy from the Sun arrives at the top of Earth's atmosphere with an intensity of \(1400 \mathrm{W} / \mathrm{m}^{2}\). How long does it take for \(1.80 \times 10^{9} \mathrm{J}\) to arrive on an area of \(1.00 \mathrm{m}^{2} ?\).

Two strings are attached to poles, however the first string is twice as long as the second. If both strings have the same tension and mu, what is the ratio of the speed of the pulse of the wave from the first string to the second string?

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