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If \(u\) is a velocity, \(x\) a length, and \(t\) a time, what are the (a) \(\partial u / \partial t\) dimensions (in the \(M L T\) system) of (b) \(\partial^{2} u / \partial x \partial t,\) and (c) \(\int(\partial u / \partial t) d x ?\)

Short Answer

Expert verified
The dimensions of (a) \(\frac{\partial u}{\partial t}\) are \([L][T]^{-2}\), (b) \(\frac{\partial^2 u}{\partial x \partial t}\) are \([L]^{-1}[T]^{-2}\), and (c) \(\int(\partial u / \partial t) dx\) are \([L]^2[T]^{-2}\) in the MLT system.

Step by step solution

01

Calculate dimensions of \(\frac{\partial u}{\partial t}\)

Velocity (\(u\)) is length per time, so its dimension is \([L][T]^{-1}\). Thus, \(\frac{\partial u}{\partial t}\) would add an extra \(1/T\) to the dimensions of \(u\), making the dimension of \(\frac{\partial u}{\partial t}\) to be \([L][T]^{-2}\).
02

Calculate dimensions of \(\frac{\partial^2 u}{\partial x \partial t}\)

From the dimensions of \(\frac{\partial u}{\partial t}\) calculated in Step 1, \(\frac{\partial^2 u}{\partial x \partial t}\) would add an extra \(1/L\) to the dimensions, since \(\partial x\) on the denominator indicates division by length. Therefore, the dimension of \(\frac{\partial^2 u}{\partial x \partial t}\) is \([L]^{-1}[T]^{-2}\).
03

Calculate dimensions of \(\int(\partial u / \partial t) dx\)

Integration will add length to the dimensions of \(\frac{\partial u}{\partial t}\), since \(\int dx\) indicates multiplication by length. Thus, the dimension of \(\int(\partial u / \partial t) dx\) would be \([L][T]^{-2} \times [L]\), which equals \([L]^2[T]^{-2}\).

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Key Concepts

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

Velocity
Velocity is a fundamental concept in physics that describes the rate at which an object changes its position. It connects the ideas of length and time by showing how much ground something can cover over a specific period. In the world of dimensions, velocity is often represented as
  • Length per unit of Time
  • Dimensions in the M L T system: - \( L \) for length - \( T^{-1} \) for time's inverse
This means that if we want to understand how fast or the speed of something over time, we use velocity. It's vital when analyzing any movement-related problem in physics.
Partial Derivatives
Partial derivatives are a type of derivative that deal with functions of several variables where we focus on changing one of these variables at a time. Unlike ordinary derivatives, which track how a single variable changes, partial derivatives allow us to explore how one factor shifts while freezing others. Imagine you're examining how velocity (\( u \)) changes over time (
  • In notation: - \( \frac{\partial u}{\partial t} \)
This shows the rate of change of velocity with respect to time). This is crucial in dynamics where multiple variables impact motion. In dimensional analysis, taking the partial derivative of a velocity
  • Adds another inverse unit of time (\( T^{-1} \))
, resulting in dimensions of
  • \( [L][T]^{-2} \)
analyzing these derivatives helps understand complex systems.
Integration
Integration is the process of finding the whole by accumulating small parts over an interval. It's the reverse of differentiation and plays a key role in calculating areas or solving differential equations. When dealing with dimensions, integration impacts them by essentially summing up small contributions over a certain variable.Consider the integral \( \int(\frac{\partial u}{\partial t}) \, dx \) In this context:
  • \( dx \) indicates accumulation across a length
    • which means multiplying by \( L \)
This changes the dimension by adding a length factor, shifting \( [L][T]^{-2} \) to
  • \( [L]^2[T]^{-2} \)
Integration is thus pivotal for finding total values associated with changes spread over a certain range, often simplifying complex calculations.
Length
In physics, length is a core concept symbolizing the mesurable distance between two points. It's the foundation upon which many other quantities, like speed and velocity, are built. When discussing dimensions, length is represented as \( [L] \).Length plays a crucial role in dimensional analysis. For example, integrating with respect to length as in \( \int \, dx \) indicates a path over which we're summing up variations. This act of accumulation often changes dimensions in analyses, adding complexity to physical calculations. Length's significance extends beyond mere distance measurement and into characterizing space and describing the scale of processes or objects being studied.
Time
Time is an essential part of how we describe the universe, providing a frame within which changes happen. In physics, the idea of time is crucial for establishing how and when events occur. Represented in the M L T system as \( [T] \), it signifies time's impact in various measurements.In dimensional analysis, time operates by modifying other dimensions. For instance, taking the partial derivative concerning time (
  • \( \frac{\partial}{\partial t} \))
    • alters the dimension by including \( T^{-1} \)
This operation has pervasive implications in motion, speed, and acceleration studies. When analyzing systems where time is a dominant factor, understanding its effect through proper dimensional handling is vital. Time's role is instrumental in shedding light on phenomena's temporal dynamics.

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Most popular questions from this chapter

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