/*! 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 19 The period of oscillation \(T\) ... [FREE SOLUTION] | 91Ó°ÊÓ

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The period of oscillation \(T\) of a water surface wave is assumed to be a function of density \(\rho,\) wavelength \(\lambda\) depth \(h,\) gravity \(g,\) and surface tension \(Y .\) Rewrite this relationship in dimensionless form. What results if \(Y\) is negligible? Hint: Take \(\lambda, \rho,\) and \(g\) as repeating variables.

Short Answer

Expert verified
The dimensionless form is \( F\left(\frac{T\sqrt{g}}{\lambda}, \frac{h}{\lambda}, \frac{Y}{\rho g \lambda^2}\right) = 0 \); if \(Y\) is negligible, \( F\left(\frac{T\sqrt{g}}{\lambda}, \frac{h}{\lambda}\right) = 0 \).

Step by step solution

01

Identify the Dimensions

First, identify the dimensions of each variable involved. The dimensions in terms of mass \(M\), length \(L\), and time \(T\) are as follows:\- Period \(T\): \([T] = T\) \- Density \(\rho\): \([\rho] = ML^{-3}\) \- Wavelength \(\lambda\): \([\lambda] = L\) \- Depth \(h\): \([h] = L\) \- Gravity \(g\): \([g] = LT^{-2}\) \- Surface Tension \(Y\): \([Y] = MT^{-2}\)
02

Select Repeating Variables

According to the question, we choose \(\lambda\), \(\rho\), and \(g\) as the repeating variables. These are chosen because they encompass the fundamental dimensions of mass \(M\), length \(L\), and time \(T\), and will help create dimensionless groups.
03

Formulate Pi Terms Using Buckingham Pi Theorem

Using the repeating variables \(\lambda\), \(\rho\), and \(g\), construct dimensionless groups (Pi terms) for each remaining variable. Define Pi terms as: \ 1. \(\Pi_1 = \lambda^a \rho^b g^c T\) which must be dimensionless. \ 2. \(\Pi_2 = \lambda^d \rho^e g^f h\) \ 3. \(\Pi_3 = \lambda^g \rho^h g^i Y\)
04

Solve for Pi terms

For \(\Pi_1 = \lambda^a \rho^b g^c T\): \ Writing the dimensional equation: \ \(L^a (ML^{-3})^b (LT^{-2})^c T = L^{a-3b+c} M^b T^{1-2c}\) \ Setting exponents to zero: \ \[ a - 3b + c = 0 \] \ \[ b = 0 \] \ \[ 1 - 2c = 0 \] \ Solve: \(b = 0, c = \frac{1}{2}, a = 0\) gives \(\Pi_1 = \sqrt{g}\cdot T/\lambda\). Apply the same principle for \(\Pi_2\) and \(\Pi_3\): \ For \(\Pi_2 = \lambda^d \rho^e g^f h\): Solve to get \(\Pi_2 = h/\lambda\). \ For \(\Pi_3 = \lambda^g \rho^h g^i Y\): Solve such that \(\Pi_3 = Y/(\rho g \lambda^2)\).
05

Establish Dimensionless Relationship

Since each \(\Pi\) term forms a dimensionless entity, the relationship in dimensionless form is: \\[ F(\Pi_1, \Pi_2, \Pi_3) = F\left(\frac{T\sqrt{g}}{\lambda}, \frac{h}{\lambda}, \frac{Y}{\rho g \lambda^2}\right) = 0 \]
06

Neglect Surface Tension

If surface tension \(Y\) is negligible, the third Pi term \(\Pi_3\) is effectively zero, simplifying the relationship to: \\[ F\left(\frac{T\sqrt{g}}{\lambda}, \frac{h}{\lambda}\right) = 0 \]

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Key Concepts

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

dimensionless analysis
Dimensionless analysis is a critical aspect of fluid mechanics, allowing us to understand how different factors interact without the need for specific units. This technique uses the Buckingham Pi Theorem to simplify complex physical relationships by reducing the number of independent variables.
By grouping the original variables into dimensionless 'Pi terms,' we can analyze the system's behavior more efficiently. For instance, instead of considering wavelength \(\lambda\), density \(\rho\), gravity \(g\), and period \(T\) separately, dimensionless analysis combines them into a single term like \(\Pi_1 = \frac{T\sqrt{g}}{\lambda}\).
  • This allows universal understanding across different systems.
  • Reduces computational complexity when solving equations.
  • Helpful in scaling physical models up or down.
By neglecting surface tension, a non-dominant factor, the analysis becomes even simpler, focusing on the major parameters influencing the waves. This approach makes complex equations more tractable and easier to experimentally validate.
surface waves
Surface waves are fascinating phenomena observed at the interface between two different media, such as water and air. These waves are governed by the interplay of fluid properties and external forces like gravity and, in some cases, surface tension.
In the exercise, surface waves' oscillation period \(T\) is influenced by several factors:
  • Gravity \(g\): Drives the wave motion, influencing the wave speed and period.
  • Wavelength \(\lambda\): The distance between successive crests of the wave.
  • Depth \(h\): Affects the wave dynamics depending on whether the water is deep or shallow relative to the wavelength.
When surface tension \(Y\) is small, its effect on the wave can be negligible, focusing the analysis on gravity-driven waves. Understanding these relationships helps in predicting waves' behavior and their impact on environments and structures.
fluid mechanics
Fluid mechanics is a fundamental branch of physics that studies the behavior of fluids—liquids, gases, and plasmas. In the context of the exercise, it provides the framework for analyzing how waves move across the water's surface.
The discipline involves principles:
  • Mass conservation, ensuring that fluid mass remains constant in closed systems.
  • Momentum conservation, dealing with forces and motions within the fluid.
  • Energy conservation, which accounts for energy transformations and losses.
By considering variables such as density \(\rho\), gravity \(g\), and surface conditions, fluid mechanics helps us understand complex interactions leading to phenomena like waves and oscillations. Through dimensionless analysis, derived from fluid mechanics, we simplify these interactions to predict and model real-world situations.
oscillation period
The oscillation period \(T\) of waves is a measure of time it takes for one complete wave cycle to pass a given point. This period is essential for understanding wave dynamics and predicting their future states.
Several factors determine the oscillation period of surface waves:
  • Density \(\rho\): Although its direct impact might be less intuitive, it influences wave behavior through buoyancy principles.
  • Gravity \(g\): Serves as the primary force affecting acceleration and deceleration of wave motion.
  • Surface tension \(Y\): Affects stability and can influence the period, although it may be neglected if insignificant compared to gravitational forces.
Analyzing the oscillation period through these variables enables the formulation of dimensionless groups like \(\frac{T\sqrt{g}}{\lambda}\), providing a clear understanding of the wave characteristics without dependence on specific units or conditions.

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