/*! 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 135 The \(6-\mathrm{kg}\) cylinder i... [FREE SOLUTION] | 91Ó°ÊÓ

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The \(6-\mathrm{kg}\) cylinder is released from rest in the position shown and falls on the spring, which has been initially precompressed \(50 \mathrm{mm}\) by the light strap and restraining wires. If the stiffness of the spring is \(4 \mathrm{kN} / \mathrm{m},\) compute the additional deflection \(\delta\) of the spring produced by the falling cylinder before it rebounds.

Short Answer

Expert verified
Additional deflection \(\delta\) is approximately 29 mm.

Step by step solution

01

Identify Initial Conditions and Forces

The cylinder has a mass of 6 kg and is initially at rest before falling on the spring. The spring is initially precompressed by 50 mm. The force due to gravity acting on the cylinder can be calculated using the formula: \( F = mg \), where \( g = 9.81 \text{ m/s}^2 \).
02

Equate Potential Energy and Spring Energy

When the cylinder falls on the spring, its potential energy is converted into the energy stored in the spring. The potential energy just before hitting the spring can be expressed as \( E_p = mgh \) where \( h \) is the height equivalent to the additional compression caused by the fall. The spring energy can be expressed as \( E_s = \frac{1}{2}k(x_0 + \delta)^2 \), where \( x_0 = 0.05 \text{ m} \) is the initial compression and \( \delta \) is the additional deflection.
03

Solve for Additional Deflection \(\delta\)

Assume the entire potential energy converts to spring energy: \( mgh = \frac{1}{2}k(x_0 + \delta)^2 \). Plug in the values: \( 6 \times 9.81 \times (x_0 + \delta) = \frac{1}{2} \times 4000 \times (0.05 + \delta)^2 \). This equation can get simplified and can be solved for \( \delta \).
04

Calculation

Expand and simplify the equation from Step 3:\( 58.86 \times (0.05 + \delta) = 2000 \times (0.05^2 + 2 \times 0.05 \times \delta + \delta^2)\). Solve this quadratic equation to find \( \delta \). On solving, you get \( \delta \approx 0.029 \text{ m} \) or 29 mm.

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Key Concepts

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

Potential Energy
Potential energy is the energy an object possesses due to its position or height above the ground. In this exercise, the 6-kg cylinder has potential energy because it is elevated above the spring. The formula for potential energy is given by \( E_p = mgh \), where \( m \) is mass, \( g \) is the acceleration due to gravity (9.81 m/s²), and \( h \) is the height of the object.

When the cylinder falls, this energy is converted into other forms, primarily into the energy stored in the spring. Understanding this conversion process is crucial in analyzing systems involving heights and potential energy.
Spring Force
The spring force is the force exerted by a spring when it is compressed or stretched. This force is governed by Hooke’s Law, which states that the force exerted by a spring is proportional to its displacement \( x \) from its rest position. This is expressed mathematically as \( F = -kx \), where \( k \) is the stiffness or spring constant, and \( x \) is the displacement from the equilibrium position.

In this problem, the spring is initially compressed by 50 mm, and we need to find the additional compression caused by the falling cylinder. With a spring constant \( k = 4000 \, \text{N/m} \), the spring's ability to resist and store energy when compressed is significant, affecting the dynamics of the entire system.
Mass-Spring System
A mass-spring system consists of a mass attached to a spring. When the mass moves, the spring compresses or extends, storing mechanical energy as potential energy, and later releasing it as kinetic energy.

In this exercise, the cylinder represents the mass in the mass-spring system. When it falls onto the spring, the entire potential energy of the cylinder (due to its height) transfers into the spring, causing it to compress further. Understanding how the mass-spring system functions helps in predicting the behavior of the spring under the weight of the mass, and is a fundamental concept in mechanical dynamics.
Energy Conversion
Energy conversion in a mechanical context often involves transforming potential energy to kinetic energy, or into energy stored in a spring. In this exercise, when the cylinder falls, potential energy due to its height gets converted completely into the stored energy of the spring as the spring compresses.

This transformation is described by the equation \( mgh = \frac{1}{2}k(x_0 + \delta)^2 \), which equates the potential energy of the cylinder to the spring energy. This equality is the basis for calculating how much the spring will compress under the weight of the falling cylinder, illustrating the principles of energy conservation and conversion.
Deflection Calculation
Deflection calculation involves determining how much a spring compresses or deflects when a force is applied. In this exercise, we aim to find the additional compression, \( \delta \), beyond the initial 50 mm precompression.

Using the equation from energy conversion, the potential energy converts into stored spring energy, leading to a quadratic equation: \[58.86 \times (0.05 + \delta) = 2000 \times (0.05^2 + 2 \times 0.05 \times \delta + \delta^2)\]Solving this equation gives the additional deflection \( \delta \), which is approximately 29 mm. Mastering deflection calculations is vital in understanding and designing systems that involve springs and other elastic materials.

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