/*! 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 26 A particle is trapped in a poten... [FREE SOLUTION] | 91Ó°ÊÓ

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A particle is trapped in a potential well described by \(U(x)=1.7 x^{2}-b\), with \(U\) in joules, \(x\) in meters, and \(b=4.4 \mathrm{~J} .\) Find the force on the particle when it's at (a) \(x=2.9 \mathrm{~m}\), (b) \(x=0\), and (c) \(x=-1.9 \mathrm{~m}\).

Short Answer

Expert verified
The force on the particle at (a) \(x = 2.9 m\) is \(-9.86 N\), (b) \(x = 0 m\) is \(0 N\), and (c) \(x = -1.9 m\) is \(6.46 N\).

Step by step solution

01

Find the equation for the force

The force on the particle is given by \(F(x) = -dU(x)/dx\), the negative derivative of the potential energy with respect to position. For the given potential energy \(U(x) = 1.7x^2 - b\), the derivative with respect to \(x\) is \(dU(x)/dx = 3.4x\). Thus, the force on the particle is \(F(x) = -3.4x\).
02

Calculate the force at \(x=2.9 m\)

Substitute \(x = 2.9 m\) into the equation for the force: \(F(2.9) = -3.4(2.9) = -9.86 N\). Therefore, the force on the particle at \(x = 2.9 m\) is -9.86 N.
03

Calculate the force at \(x=0\)

Substitute \(x = 0\) into the equation for the force: \(F(0) = -3.4(0) = 0 N\). Therefore, there is no force on the particle at \(x = 0 m\).
04

Calculate the force at \(x=-1.9 m\)

Substitute \(x = -1.9 m\) into the equation for the force: \(F(-1.9) = -3.4(-1.9) = 6.46 N\). Therefore, the force on the particle at \(x = -1.9 m\) is 6.46 N.

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Key Concepts

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

Force on a Particle
Understanding the force experienced by a particle in a potential well is crucial in physics. This force is the mechanism by which the particle's motion can be changed. According to Newton's second law, force is the product of mass and acceleration, but in the context of potential wells, we also consider force as the negative gradient of potential energy.

To put it simply, if you picture a marble in a bowl, the marble will roll toward the bottom of the bowl. The sides of the bowl provide a force pushing the marble downwards, seeking the lowest potential energy position. In this case, the bowl's shape is analogous to the potential well in our exercise.

By following the equation \(F(x) = -dU(x)/dx\), you can determine the force on the particle at any point in the potential well. This equation illustrates how force relates to the derivative of potential energy with respect to position. The negative sign indicates that the force acts in the opposite direction of increasing potential energy. With the given potential energy function, \(U(x) = 1.7x^2 - b\), taking the derivative provides us with a straightforward linear relation between force and position, \(F(x) = -3.4x\). Through this relationship, you can predict how the particle will move within the well.
Derivative of Potential Energy
The derivative of potential energy with respect to position tells us how the potential energy changes as a particle moves through space. It's a concept that at first may seem challenging, but it's quite an intuitive measure once understood. Essentially, it gives us the slope of the potential energy curve at any given point. A steeper slope means a larger change in potential energy over a shorter distance, which corresponds to a stronger force.

In our exercise, the derivative is given as \(dU(x)/dx = 3.4x\), which tells us that as the particle moves away from the origin, the force (and thus the potential energy) changes more dramatically the farther from the origin it is. At the origin, where \(x=0\), there is no change in potential energy—this is where the particle experiences no force and would remain at rest if undisturbed. This concept is a stepping stone for predicting how the particle will behave under different conditions within the potential well.
Potential Energy Function
The potential energy function is a vital concept for visualizing and calculating the energy landscape within which a particle moves. It's a mathematical description of how potential energy varies with position. In our scenario, the potential energy function \(U(x) = 1.7x^2 - b\) represents a parabolic well, where the lowest point, the vertex, is shifted by the constant \(b\).

The function is akin to a map that guides the particle's journey. Imagine hiking in a valley—the shape of the valley influences how you would move and where you could rest without sliding down. In this metaphor, the valley's shape corresponds to the potential energy function of the particle. For the particle in our exercise, the potential energy at the bottom of the well is the lowest due to the negative constant \(b\), and this is where the particle has the least energy and could theoretically stay at rest if not acted upon by other forces.

The quadratic term \(1.7x^2\) indicates that the potential energy increases more rapidly as the particle moves farther from the center of the well (the origin). This shape affects the magnitude and direction of the force on the particle within the well, determining the particle's motion and stability.

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