/*! 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 57 A \(2 \mathrm{~kg}\) block is la... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

A \(2 \mathrm{~kg}\) block is launched up a frictionless inclined plane by a spring as shown in Figure 5.68 . The plane is inclined at \(30^{\circ}\), and the spring constant is \(1000 \mathrm{~N} / \mathrm{m}\). The block is initially pushed against the spring in order to compress the spring \(0.1 \mathrm{~m},\) and then it is released. (a) Calculate the magnitude and direction of the acceleration of the block the moment after it is released. (b) Calculate the acceleration when the spring reaches the point where its compression is \(0.05 \mathrm{~m}\). (c) What are the magnitude and direction of the acceleration when the spring reaches the point where its compression is zero?

Short Answer

Expert verified
(a) -45.1 m/s² up the incline. (b) -20.1 m/s² up the incline. (c) -4.9 m/s² down the incline.

Step by step solution

01

Find the Initial Force Exerted by the Spring

The force exerted by the spring when compressed can be calculated using Hooke's Law: \[ F_s = -kx \] where \( k = 1000 \, \text{N/m} \) is the spring constant and \( x = 0.1 \, \text{m} \) is the compression distance. Thus, \[ F_s = -(1000)(0.1) = -100 \, \text{N} \] The negative sign indicates that the force direction is opposite to the compression direction.
02

Calculate the Net Force on the Block at Initial Release

The block is on an inclined plane, so the gravitational force has a component down the incline. The gravitational force component \( F_g \) acting down the incline can be calculated as: \[ F_g = mg \sin \theta \] where \( m = 2 \, \text{kg} \), \( g = 9.8 \, \text{m/s}^2 \), and \( \theta = 30^\circ \). Thus, \[ F_g = 2 \times 9.8 \times \sin(30) = 9.8 \, \text{N} \] The net force, \( F_{net} \), is then: \[ F_{net} = F_s - F_g = -100 + 9.8 = -90.2 \, \text{N} \] The negative sign indicates that the net force is directed up the incline.
03

Determine Initial Acceleration using Newton’s Second Law

Using Newton’s second law, \( F = ma \), the acceleration \( a \) is: \[ a = \frac{F_{net}}{m} = \frac{-90.2}{2} = -45.1 \, \text{m/s}^2 \] The acceleration is directed up the incline.
04

Calculate Force and Acceleration at Compression of 0.05 m

With the spring compressed by \( 0.05 \, \text{m} \), the spring force \( F_s \) is: \[ F_s = -kx = -(1000)(0.05) = -50 \, \text{N} \] The net force \( F_{net} \) at \( 0.05 \, \text{m} \) compression is: \[ F_{net} = F_s - F_g = -50 + 9.8 = -40.2 \, \text{N} \] Then, the acceleration is: \[ a = \frac{F_{net}}{m} = \frac{-40.2}{2} = -20.1 \, \text{m/s}^2 \] The acceleration is again directed up the incline.
05

Calculate Force and Acceleration when Compression is Zero

When the spring reaches zero compression, the spring force \( F_s \) is \( 0 \, \text{N} \). The gravitational force component \( F_g = 9.8 \, \text{N} \) remains the same. The net force \( F_{net} \) is then: \[ F_{net} = 0 - 9.8 = -9.8 \, \text{N} \] And the acceleration is: \[ a = \frac{F_{net}}{m} = \frac{-9.8}{2} = -4.9 \, \text{m/s}^2 \] The acceleration is directed down the incline.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

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

Hooke's Law
Hooke's Law describes the relationship between the force exerted by a spring and its displacement from equilibrium. Mathematically, it is represented as \( F = -kx \). The constant \( k \) is the spring constant, indicating the stiffness of the spring, while \( x \) is the displacement. When a spring is compressed or stretched, it exerts a force in the opposite direction of the displacement. In the context of the inclined plane problem, the block compresses the spring by \( 0.1 \, \text{m} \). Using Hooke's Law, we calculate the spring force \( F_s \) as \( -100 \, \text{N} \). The negative sign signifies that this force acts in the opposite direction to the spring's compression, essentially "pushing back" against the block."
Newton's Second Law
Newton's Second Law of Motion states that the acceleration of an object is directly proportional to the net force acting upon it and inversely proportional to its mass. It is mathematically expressed as \( F = ma \), where \( F \) is the net force, \( m \) is the mass, and \( a \) is the acceleration. When applying this law to our problem, after identifying the net force exerted on the block by both the spring and gravity, we can determine the block's resulting acceleration. At initial release, the net force on the block is \( -90.2 \, \text{N} \), leading to an acceleration of \( -45.1 \, \text{m/s}^2 \). The negative sign indicates that the acceleration is directed up the plane, opposing the gravitational pull.
Spring Force
The spring force is the result of a spring being either compressed or extended from its natural position. Hooke's Law introduces this concept, which implies that the force exerted by the spring is proportional to the displacement. With the inclined plane scenario, as the spring is compressed by different amounts, the force varies: - For an initial compression of \( 0.1 \, \text{m} \), the force is \(-100 \, \text{N} \). - When the spring is compressed by \( 0.05 \, \text{m} \), the force is reduced to \( -50 \, \text{N} \). - Ultimately, when the spring returns to its natural position, the force becomes \( 0 \, \text{N} \).The variations in spring force clearly affect the net force and consequently, the acceleration of the block.
Inclined Plane Physics
Inclined planes are surfaces angled against horizontal surfaces. They are essential in physics for illustrating components of forces, especially when encountering gravitational force. In this exercise, the plane is inclined at \( 30^{\circ} \). Gravitational force acting on the block has two components: parallel and perpendicular to the inclined plane. The component acting down the incline is \( F_g = mg \sin \theta \). This component must be considered when calculating the net force and subsequent acceleration of the block as it moves up and down the plane.By understanding these force components, students can better predict how forces work on inclined planes and analyze motion effectively.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

At a construction site, a \(22.0 \mathrm{~kg}\) bucket of concrete is connected over a very light frictionless pulley to a \(375 \mathrm{~N}\) box on the roof of a building. (See Figure \(5.55 .)\) There is no appreciable friction on the box, since it is on roller bearings. The box starts from rest. (a) Make free- body diagrams of the bucket and the box. (b) Find the acceleration of the bucket. (c) How fast is the bucket moving after it has fallen \(1.50 \mathrm{~m}\) (assuming that the box has not yet reached the edge of the roof)?

People who do chin-ups raise their chin just over a bar (the chinning bar), supporting themselves only by their arms. Typically, the body below the arms is raised by about \(30 \mathrm{~cm}\) in a time of \(1.0 \mathrm{~s},\) starting from rest. Assume that the entire body of a \(680 \mathrm{~N}\) person who is chinning is raised this distance and that half the \(1.0 \mathrm{~s}\) is spent accelerating upward and the other half accelerating downward, uniformly in both cases. Make a free-body diagram of the person's body, and then apply it to find the force his arms must exert on him during the accelerating part of the chin-up.

A large fish hangs from a spring balance supported from the roof of an elevator. (a) If the elevator has an upward acceleration of \(2.45 \mathrm{~m} / \mathrm{s}^{2}\) and the balance reads \(60.0 \mathrm{~N},\) what is the true weight of the fish? (b) Under what circumstances will the balance read \(35.0 \mathrm{~N} ?\) (c) What will the balance read if the elevator cable breaks?

A \(2 \mathrm{~kg}\) book sits at rest on a horizontal table. The coefficient of static friction between the book and the surface is \(0.40,\) and the coefficient of kinetic friction is 0.20 . (a) What is the normal force acting on the book? (b) Is there a friction force on the book? (c) What minimum horizontal force would be required to cause the book to slide on the table? (d) If you give the book a strong horizontal push so that it begins sliding, what kind of force will cause it to come to rest? (e) What is the magnitude of this force?

A person pushes on a stationary \(125 \mathrm{~N}\) box with \(75 \mathrm{~N}\) at \(30^{\circ}\) below the horizontal, as shown in Figure 5.61 . The coefficient of static friction between the box and the horizontal floor is 0.80 . (a) Make a free-body diagram of the box. (b) What is the normal force on the box? (c) What is the friction force on the box? (d) What is the largest the friction force could be? (e) The person now replaces his push with a \(75 \mathrm{~N}\) pull at \(30^{\circ}\) above the horizontal. Find the normal force on the box in this case.

See all solutions

Recommended explanations on Physics Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.