/*! 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 23 A vertical spring (spring consta... [FREE SOLUTION] | 91Ó°ÊÓ

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A vertical spring (spring constant 5 112 N/m) is mounted on the fl oor. A 0.400-kg block is placed on top of the spring and pushed down to start it oscillating in simple harmonic motion. The block is not attached to the spring. (a) Obtain the frequency (in Hz) of the motion. (b) Determine the amplitude at which the block will lose contact with the spring.

Short Answer

Expert verified
(a) The frequency is approximately 2.66 Hz. (b) The amplitude at which the block loses contact is approximately 0.035 m.

Step by step solution

01

Understand the problem

A spring with a known spring constant and mass is used to determine the frequency of motion and the amplitude at which the block loses contact with the spring during its oscillation.
02

Identify the given values

We are provided with the spring constant \( k = 112 \, \text{N/m} \) and the mass of the block \( m = 0.400 \, \text{kg} \).
03

Solve for the frequency of oscillation

The formula for the frequency of simple harmonic motion is \( f = \frac{1}{2\pi} \sqrt{\frac{k}{m}} \). Substitute the values, \( k = 112 \, \text{N/m} \) and \( m = 0.400 \, \text{kg} \), to get \( f = \frac{1}{2\pi} \sqrt{\frac{112}{0.400}} \). Calculate to find \( f \approx 2.66 \, \text{Hz} \).
04

Understand the condition for losing contact

The block will lose contact with the spring when the spring force becomes zero at the maximum stretch, leading to zero normal force acting on the block.
05

Calculate maximum acceleration before losing contact

The condition for losing contact occurs when the gravitational force equals the spring force at the amplitude point, meaning \( ma = mg \). Thus, \( a = g = 9.8 \, \text{m/s}^2 \).
06

Solve for amplitude when losing contact

Using \( a = \omega^2 A \), where \( \omega = \sqrt{\frac{k}{m}} \), we can solve for the amplitude \( A \) as \( A = \frac{g}{\omega^2} \). No direct velocities or displacements are initially needed beyond this calculation to find \( A \). Substitute given values to find \( A = \frac{9.8}{\left(\sqrt{\frac{112}{0.400}}\right)^2} \approx 0.035 \).
07

Check calculations for consistency

Verify the steps taken with calculated values to ensure no numerical or algebraic errors. For the frequency \( f \), confirm using the correct units, and for amplitude \( A \), ensure alignment with initial analytic predictions.

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Key Concepts

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

Spring Constant
The spring constant, often denoted by the symbol \( k \), is a crucial parameter in a mass-spring system. It measures the stiffness of the spring and is expressed in newtons per meter (N/m).
The higher the spring constant, the stiffer the spring is, meaning it requires more force to stretch or compress by a certain distance.
In the exercise, the spring constant is given as \( 112 \, \text{N/m} \), meaning the spring is reasonably stiff. This stiffness affects both the frequency of oscillation and the potential energy stored in the system when the spring is compressed or stretched.
Understanding the spring constant helps in determining how the system will behave under various forces, including how quickly it will oscillate and the maximum amplitude of these oscillations.
Frequency of Oscillation
Frequency of oscillation refers to how many cycles an oscillating system completes in one second.
In simple harmonic motion, the frequency \( f \) can be determined by the formula:
\[ f = \frac{1}{2\pi} \sqrt{\frac{k}{m}} \]
where \( k \) is the spring constant and \( m \) is the mass.
For the given problem, substituting \( k = 112 \, \text{N/m} \) and \( m = 0.400 \, \text{kg} \), we calculate:
\[ f \approx 2.66 \, \text{Hz} \]
This means the block, once pushed, will complete about 2.66 cycles per second.
Understanding frequency is vital in predicting the behavior of a mass-spring system, especially when designed to work acoustically or mechanically.
Amplitude
Amplitude in the context of simple harmonic motion refers to the maximum extent of movement of the oscillating object from its equilibrium position.
The amplitude is a crucial factor because it indicates the energy level of the system and can affect whether an object loses contact with the spring in vertical motions.
According to the problem, the amplitude at which the block loses contact is where the spring force can no longer counteract gravity. The condition for losing contact occurs when:
  • The spring force and gravitational force balance (i.e., \( ma = mg \)).
  • This leads to the calculation: \( A = \frac{g}{\omega^2} \)
  • With calculated amplitude \( A \approx 0.035 \)
Thus, at approximately \( 0.035 \text{m} \), the block will start to lose contact with the spring as it oscillates.
Mass-Spring System
The mass-spring system is a classic example of simple harmonic oscillation, where an object of mass \( m \) is attached to a spring with stiffness \( k \).
In this system, the block and spring work together to create repetitive motion back and forth around an equilibrium position.
The two opposing forces involved are the restoring force of the spring, which tries to return the mass to the equilibrium position, and the inertial force of the mass, which drives it away.
Key characteristics of such systems include:
  • The natural frequency of oscillation, determined by both the mass and spring constant.
  • The potential for energy transfer between kinetic and potential energy during oscillation.
  • The ability to apply these principles to many real-world systems, such as car suspensions and measuring scales.
Understanding these dynamics allows for predictive modeling and analysis of many mechanical systems using just a mass and a spring.

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Most popular questions from this chapter

An object attached to a horizontal spring is oscillating back and forth along a frictionless surface. The maximum speed of the object is \(1.25 \mathrm{m} / \mathrm{s},\) and its maximum acceleration is \(6.89 \mathrm{m} / \mathrm{s}^{2} .\) How much time elapses between an instant when the object's speed is at a maximum and the next instant when its acceleration is at a maximum?

ao \(A\) spring lies on a horizontal table, and the left end of the spring is attached to a wall. The other end is connected to a box. The box is pulled to the right, stretching the spring. Static friction exists between the box and the table, so when the spring is stretched only by a small amount and the box is released, the box does not move. The mass of the box is \(0.80 \mathrm{kg},\) and the spring has a spring constant of \(59 \mathrm{N} / \mathrm{m} .\) The coefficient of static friction between the box and the table on which it rests is \(\mu_{\mathrm{s}}=0.74\) How far can the spring be stretched from its unstrained position without the box moving when it is released?

A 59-kg water skier is being pulled by a nylon tow rope that is attached to a boat. The unstretched length of the rope is \(12 \mathrm{m},\) and its crosssectional area is \(2.0 \times 10^{-5} \mathrm{m}^{2} .\) As the skier moves, a resistive force (due to the water) of magnitude \(130 \mathrm{N}\) acts on her; this force is directed opposite to her motion. What is the change in the length of the rope when the skier has an acceleration whose magnitude is \(0.85 \mathrm{m} / \mathrm{s}^{2} ?\)

A 15.0-kg block rests on a horizontal table and is attached to one end of a mass less, horizontal spring. By pulling horizontally on the other end of the spring, someone causes the block to accelerate uniformly and reach a speed of 5.00 m/s in 0.500 s. In the process, the spring is stretched by 0.200 m. The block is then pulled at a constant speed of 5.00 m/s, during which time the spring is stretched by only 0.0500 m. Find (a) the spring constant of the spring and (b) the coefficient of kinetic friction between the block and the table.

\(\mathrm{A}\) square plate is \(1.0 \times 10^{-2} \mathrm{m}\) thick, measures \(3.0 \times 10^{-2} \mathrm{m}\) on a side, and has a mass of \(7.2 \times 10^{-2} \mathrm{kg} .\) The shear modulus of the material is \(2.0 \times 10^{10} \mathrm{N} / \mathrm{m}^{2} .\) One of the square faces rests on a flat horizontal surface, and the coefficient of static friction between the plate and the surface is 0.91. A force is applied to the top of the plate, as in Figure 10.29 a. Determine (a) the maximum possible amount of shear stress, (b) the maximum possible amount of shear strain, and (c) the maximum possible amount of shear deformation \(\Delta X\) (see Figure \(10.29 b\) ) that can be created by the applied force just before the plate begins to move.

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