/*! 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 16 16\. Two Blocks In Fig. 16-32 tw... [FREE SOLUTION] | 91Ó°ÊÓ

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16\. Two Blocks In Fig. 16-32 two blocks \((m=1.0 \mathrm{~kg}\) and \(M=\) \(10 \mathrm{~kg}\) ) and a spring \((k=200 \mathrm{~N} / \mathrm{m})\) are arranged on a horizontal, frictionless surface. The coefficient of static friction between the two blocks is \(0.40\). What amplitude of simple harmonic motion of the spring-blocks system puts the smaller block on the verge of slipping over the larger block?

Short Answer

Expert verified
The amplitude is approximately 0.215 m.

Step by step solution

01

Identify the forces

First, determine the force due to friction that is acting on the smaller block. The maximum static friction force can be calculated using the formula: \[ f_{\text{max}} = \text{static friction coefficient} \times \text{normal force} \] Here, the normal force is equal to the weight of the smaller block, which is \( m \times g \).
02

Calculate the maximum static friction force

Using the given values: \[ f_{\text{max}} = 0.40 \times (1 \times 9.8) = 3.92 \text{ N} \] This is the maximum force that static friction can exert on the smaller block to prevent it from slipping.
03

Determine the maximum acceleration

The maximum static friction force is equal to the maximum horizontal force that can be applied to the smaller block without it slipping. Using Newton's second law, this force is also equal to the product of the smaller block's mass and its maximum acceleration: \[ f_{\text{max}} = m \times a_{\text{max}} \] Solving for \( a_{\text{max}} \), we have: \[ a_{\text{max}} = \frac{f_{\text{max}}}{m} = \frac{3.92}{1} = 3.92 \text{ m/s}^2 \]
04

Relate maximum acceleration to amplitude

In simple harmonic motion, the maximum acceleration \( a_{\text{max}} \) is related to the angular frequency \( \omega \) and the amplitude \( A \) by the equation: \[ a_{\text{max}} = \omega^2 \times A \] The angular frequency \( \omega \) is related to the spring constant \( k \) and the total mass \( (m+M) \) of the system: \[ \omega = \sqrt{\frac{k}{m+M}} \] Substituting the values: \[ \omega = \sqrt{\frac{200}{1+10}} = \sqrt{\frac{200}{11}}\approx 4.27 \text{ rad/s} \]
05

Solve for amplitude

Using the relationship between maximum acceleration and amplitude: \[ 3.92 = (4.27)^2 \times A \] Solving for amplitude \( A \): \[ A = \frac{3.92}{(4.27)^2} \] \[ A \approx \frac{3.92}{18.22} \approx 0.215 \text{ m} \]

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Key Concepts

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

simple harmonic motion
Simple harmonic motion refers to a type of periodic motion where the restoring force is directly proportional to the displacement and acts in the direction opposite to that of displacement. Imagine a spring-block system where a block is attached to a spring. When the block is pulled and then released, it will move back and forth around its equilibrium position. This back-and-forth motion is what we call simple harmonic motion (SHM). In SHM, the motion can be described using sine or cosine functions, and it is characterized by an amplitude (the maximum distance from the equilibrium position), a period (the time it takes to complete one full cycle), and the angular frequency.
static friction
Static friction is the frictional force that prevents two surfaces from sliding past each other. It acts when an object is stationary and ensures that it does not start moving in response to applied forces. The maximum static friction force is given by the product of the coefficient of static friction (a constant that depends on the materials in contact) and the normal force (the force perpendicular to the surfaces in contact).
For our problem, the static friction plays a crucial role. We need to find the maximum amplitude of the spring-block system's simple harmonic motion that will not cause the smaller block to slip. If the spring causes too much acceleration, the static friction will not be able to prevent slipping.
angular frequency
Angular frequency is a measure of how quickly an object moves through its cycle of simple harmonic motion and is denoted by \( \omega \). The angular frequency is related to the spring constant \( k \) and the total mass of the system \( m + M \). It can be calculated using the formula:
\[ \omega = \sqrt{\frac{k}{m+M}} \]
In our example, we substitute the values: the spring constant \( k = 200 \) N/m and the total mass \( m + M = 1 + 10 = 11 \) kg. This gives:
\[ \omega = \sqrt{\frac{200}{11}} \approx 4.27 \text{ rad/s} \]. This angular frequency tells us how fast the system oscillates.
maximum acceleration
In simple harmonic motion, the maximum acceleration occurs at the maximum displacement, or amplitude, from the equilibrium position. The relationship between the maximum acceleration \( a_{max} \) and amplitude A is given by:
\[ a_{max} = \omega^2 \times A \]
Given \( a_{max} = 3.92 \text{ m/s}^2 \) (calculated from the maximum static friction force) and \( \omega = 4.27 \text{ rad/s} \), we solve for the amplitude A:
\[ A = \frac{a_{max}}{\omega^2} \]
Substitution gives:
\[ A = \frac{3.92}{(4.27)^2} \approx 0.215 \text{ m} \]. The amplitude must not exceed this value to prevent the smaller block from slipping.
Spring-block system
A spring-block system consists of a block attached to a spring, and it often oscillates in simple harmonic motion when displaced from its equilibrium position. In our problem, we have two blocks and a horizontal spring on a frictionless surface. The spring constant (stiffness) of the spring is given as 200 N/m. The goal is to ensure the smaller block, due to the static friction between the blocks, does not slip over the larger block when the system is oscillating.
This system's behavior is pivotal for understanding many physical situations where forces and motion are involved, such as vibrations in mechanical structures, the behavior of molecules, and even the basics of many instruments in physics.

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Most popular questions from this chapter

12\. A Body Oscillates A body oscillates with simple harmonic motion according to the equation $$ x=(6.0 \mathrm{~m}) \cos [(3 \pi \mathrm{rad} / \mathrm{s}) t+\pi / 3 \mathrm{rad}] $$ At \(t=2.0 \mathrm{~s}\), what are (a) the displacement, (b) the velocity, (c) the acceleration, and (d) the phase of the motion? Also, what are (e) the frequency and (f) the period of the motion?

11\. Automobile Spring An automobile can be considered to be mounted on four identical springs as far as vertical oscillations are concerned. The springs of a certain car are adjusted so that the oscillations have a frequency of \(3.00 \mathrm{~Hz}\). (a) What is the spring constant of each spring if the mass of the car is \(1450 \mathrm{~kg}\) and the mass is evenly distributed over the springs? (b) What will be the oscillation frequency if five passengers, averaging \(73.0 \mathrm{~kg}\) each, ride in the car? (Again, consider an even distribution of mass.)

48\. Large Slingshot A (hypothetical) large slingshot is stretched \(1.50 \mathrm{~m}\) to launch a \(130 \mathrm{~g}\) projectile with speed sufficient to escape from Earth \((11.2 \mathrm{~km} / \mathrm{s})\). Assume the elastic bands of the slingshot obey Hooke's law. (a) What is the spring constant of the device, if all the elastic potential energy is converted to kinetic energy? (b) Assume that an average person can exert a force of \(220 \mathrm{~N}\). How many people are required to stretch the elastic bands?

17\. Shake Table A block is on a horizontal surface (a shake table) that is moving back and forth horizontally with simple harmonic motion of frequency \(2.0 \mathrm{~Hz} .\) The coefficient of static friction between block and surface is \(0.50 .\) How great can the amplitude of the SHM be if the block is not to slip along the surface?

37\. Pivoting Long Rod A pendulum is formed by pivoting a long thin rod of length \(L\) and mass \(m\) about a point on the rod that is a distance \(d\) above the center of the rod. (a) Find the period of this pendulum in terms of \(d, L, m\), and \(g\), assuming small-amplitude swinging. What happens to the period if (b) \(d\) is decreased, (c) \(L\) is increased, or (d) \(m\) is increased?

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