/*! 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 77 As a particle moves along an \(x... [FREE SOLUTION] | 91Ó°ÊÓ

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As a particle moves along an \(x\) axis, a force in the positive direction of the axis acts on it. Figure \(7-50\) shows the magnitude \(F\) of the force versus position \(x\) of the particle. The curve is given by \(F=a / x^{2}\), with \(a=9.0 \mathrm{~N} \cdot \mathrm{m}^{2} .\) Find the work done on the particle by the force as the particle moves from \(x=1.0 \mathrm{~m}\) to \(x=3.0 \mathrm{~m}\) by \((\mathrm{a})\) estimating the work from the graph and (b) integrating the force function.

Short Answer

Expert verified
The work done is approximately 6.0 J, as calculated by integrating.

Step by step solution

01

Understanding the Problem

To find the work done as the particle moves from \(x = 1.0\, \text{m}\) to \(x = 3.0\, \text{m}\), we need to calculate the area under the curve of \(F(x) = \frac{a}{x^2}\) where \(a = 9.0\, \text{N} \cdot \text{m}^2\). First, we'll estimate this area by considering the curve's general shape.
02

Estimating the Work from the Graph

Estimate areas by assuming a shape (like trapezoids or rectangles), approximating the work done. Assume approximate areas from the curve between \(x = 1.0\, \text{m}\) and \(x = 3.0\, \text{m}\). This method gives an approximate value, useful for a quick check.
03

Setting Up the Integral

The work done by a varying force can be calculated exactly by integrating the force function over the interval. Set up the integral for the work done from \(x=1.0\) to \(x=3.0\): \[ W = \int_{1.0}^{3.0} \frac{9.0}{x^2} \, dx. \]
04

Integrating the Force Function

Perform the integration: \[ \int \frac{9.0}{x^2} \, dx = -\frac{9.0}{x}. \] Evaluate from \(1.0\) to \(3.0\): \[ W = \left[ -\frac{9.0}{x} \right]_{1.0}^{3.0} = -\frac{9.0}{3.0} + \frac{9.0}{1.0} = -3.0 + 9.0 = 6.0. \]
05

Concluding the Calculation

The integration shows that the exact work done on the particle is \(6.0\, \text{J}\). Hence, while an estimate from the graph might slightly differ, the integrated value is precise.

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Key Concepts

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

Integral Calculus
Integral calculus is a branch of mathematics focused on the concept of integration, which allows us to find the accumulation of quantities, such as areas under curves. In this exercise, integration helps to calculate the work done by a force as a particle moves along a specific path. To determine the work done on the particle by the force, we compute the definite integral of the force function over the given interval.
  • The force function is given as \( F(x) = \frac{a}{x^2} \), with \( a = 9.0 \, \text{N}\cdot \text{m}^2 \).
  • The limits of the integral are from \( x = 1.0 \, \text{m} \) to \( x = 3.0 \, \text{m} \).
By solving \( \int_{1.0}^{3.0} \frac{9.0}{x^2} \, dx \), we find the accumulation of work over this interval, resulting in \( 6.0 \, \text{J} \). This result represents the precise work done, differing from an estimation that one might make by guessing at the area visually on a graph. Integration hence provides a powerful tool to precisely understand how forces accumulate over particle motion along a path.
Particle Motion
Understanding particle motion involves knowing both the path of the particle and the forces acting along that path. In this exercise, the particle moves along the x-axis, influenced by a force that varies with its position. The motion of the particle:
  • Occurs along a straight path on the x-axis from \( x = 1.0 \, \text{m} \) to \( x = 3.0 \, \text{m} \).
  • Is influenced by a force function that diminishes as the distance \( x \) increases, represented by \( F(x) = \frac{a}{x^2} \).
Particle motion, in this case, gives insight into how varying forces play a role in changing the particle's position and momentum over this interval. By solving for the work done, we can directly see how much energy is transferred to the particle as it moves. This understanding is not just crucial for physics problems, but also for designing systems where precise control of motion is necessary.
Force Function
The force function in this exercise is a mathematical representation of how the force changes with respect to the position of the particle along its path. The specific force function given is \( F(x) = \frac{a}{x^2} \), where \( a = 9.0 \, \text{N} \cdot \text{m}^2 \). This means:
  • The force decreases as \( x \) increases because it is inversely proportional to \( x^2 \).
  • At \( x = 1.0 \, \text{m} \), the force magnitude is higher compared to \( x = 3.0 \, \text{m} \).
  • This function is a classic example of an inverse square law, commonly seen in physics, such as gravitational or electrostatic forces.
Understanding the force function is vital because it reveals how non-uniform forces cause different energy transfers depending on specific positions along the particle's trajectory. This knowledge allows us to integrate the force function across a given path to compute the total work done by such forces. Such insights are crucial in fields ranging from engineering to astronomy, where forces often do not act uniformly.

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Most popular questions from this chapter

The force on a particle is directed along an \(x\) axis and given by \(F=F_{0}\left(x / x_{0}-1\right)\). Find the work done by the force in moving the particle from \(x=0\) to \(x=2 x_{0}\) by (a) plotting \(F(x)\) and measuring the work from the graph and (b) integrating \(F(x)\).

(a) At a certain instant, a particle-like object is acted on by a force \(\vec{F}=(4.0 \mathrm{~N}) \hat{\mathrm{i}}-(2.0 \mathrm{~N}) \hat{\mathrm{j}}+(9.0 \mathrm{~N}) \hat{\mathrm{k}}\) while the object's velocity is \(\vec{v}=-(2.0 \mathrm{~m} / \mathrm{s}) \hat{\mathrm{i}}+(4.0 \mathrm{~m} / \mathrm{s}) \hat{\mathrm{k}} .\) What is the instantaneous rate at which the force does work on the object? (b) At some other time, the velocity consists of only a \(y\) component. If the force is unchanged and the instantaneous power is \(-12 \mathrm{~W},\) what is the velocity of the object?

If a ski lift raises 100 passengers averaging \(660 \mathrm{~N}\) in weight to a height of \(150 \mathrm{~m}\) in \(60.0 \mathrm{~s}\), at constant speed, what average power is required of the force making the lift?

If a Saturn \(\mathrm{V}\) rocket with an Apollo spacecraft attached had a combined mass of \(2.9 \times 10^{5} \mathrm{~kg}\) and reached a speed of \(11.2 \mathrm{~km} / \mathrm{s}\), how much kinetic energy would it then have?

A luge and its rider, with a total mass of \(85 \mathrm{~kg}\), emerge from a downhill track onto a horizontal straight track with an initial speed of \(37 \mathrm{~m} / \mathrm{s} .\) If a force slows them to a stop at a constant rate of \(2.0 \mathrm{~m} / \mathrm{s}^{2}\) (a) what magnitude \(F\) is required for the force, (b) what distance \(d\) do they travel while slowing, and (c) what work \(W\) is done on them by the force? What are (d) \(F,(\mathrm{e}) d,\) and \((\mathrm{f}) \mathrm{W}\) if they, instead, slow at \(4.0 \mathrm{~m} / \mathrm{s}^{2} ?\)

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