/*! 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 54 \(\bullet\) You find that if you... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

\(\bullet\) You find that if you hang a 1.25 \(\mathrm{kg}\) weight from a vertical spring, it stretches 3.75 \(\mathrm{cm} .\) (a) What is the force constant of this spring in \(\mathrm{N} / \mathrm{m}\) ? (b) How much mass should you hang from the spring so it will stretch by 8.13 \(\mathrm{cm}\) from its original, unstretched length?

Short Answer

Expert verified
(a) The force constant is 326.67 N/m. (b) Hang approximately 2.71 kg to stretch the spring 8.13 cm.

Step by step solution

01

Identify Given Variables and Equations

We are given the mass of the weight, \( m = 1.25 \, \mathrm{kg} \), and the stretch of the spring, \( x = 3.75 \, \mathrm{cm} = 0.0375 \, \mathrm{m} \). The force due to gravity is \( F = mg \), where \( g = 9.8 \, \mathrm{m/s^2} \). To find the spring constant \( k \), we use Hooke's Law \( F = kx \).
02

Calculate the Force Exerted by the Weight

Calculate the gravitational force (weight) exerted by the mass: \[ F = mg = 1.25 \, \mathrm{kg} \times 9.8 \, \mathrm{m/s^2} = 12.25 \, \mathrm{N} \]
03

Calculate the Force Constant \( k \)

Use Hooke's Law to solve for \( k \): \[ k = \frac{F}{x} = \frac{12.25 \, \mathrm{N}}{0.0375 \, \mathrm{m}} = 326.67 \, \mathrm{N/m} \]
04

Solve for Required Mass for Larger Stretch

Now, given a new displacement \( x_2 = 8.13 \, \mathrm{cm} = 0.0813 \, \mathrm{m} \), we need to find the mass \( m_2 \) that causes this stretch. Use \( F = kx \) to find \( F_2 \), and then solve \( mg = F_2 \).Using \( k = 326.67 \, \mathrm{N/m} \), calculate:\[ F_2 = k \times x_2 = 326.67 \, \mathrm{N/m} \times 0.0813 \, \mathrm{m} = 26.56 \, \mathrm{N} \]Now solve for \( m_2 \):\[ m_2 = \frac{F_2}{g} = \frac{26.56 \, \mathrm{N}}{9.8 \, \mathrm{m/s^2}} \approx 2.71 \, \mathrm{kg} \]
05

Conclusion

We have found the force constant \( k \) to be approximately 326.67 \( \mathrm{N/m} \) and the mass required to stretch the spring by 8.13 cm is approximately 2.71 kg.

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.

Spring Constant Calculation
Understanding how to calculate the spring constant is crucial when dealing with problems involving springs and stretches. To start, we apply Hooke's Law, which states that the force exerted by a spring is directly proportional to the displacement of the spring from its equilibrium position. This can be summarized by the equation: \ F = kx.
Here, \( F \) is the force applied (measured in Newtons), \( k \) is the spring constant (measured in Newtons per meter), and \( x \) is the displacement of the spring (in meters). Knowing these relationships allows us to find the spring constant easily when we have values for force and displacement.
For example, if we have a spring that stretches 0.0375 meters under a force of 12.25 Newtons, we can rearrange Hooke's Law to solve for the spring constant: \ \( k = \frac{F}{x} \).
This shows that the spring constant \( k \) quantifies the stiffness of the spring. A higher \( k \) value indicates a stiffer spring that requires more force to achieve the same amount of displacement compared to one with a smaller \( k \).

Remember, not all springs will have the same constant, as it depends on the material and construction. This calculation is fundamental in many engineering and physics applications, particularly in scenarios where precise force application is necessary.
Mass and Weight
Mass and weight are often confused terms, but they refer to different physical properties. It's important to clarify this distinction for problems like the one in our exercise.
  • Mass is a measure of the amount of matter in an object. It's a scalar quantity and is measured in kilograms (kg).
  • Weight, on the other hand, is the force exerted by gravity on an object's mass. It's a vector quantity and measured in Newtons (N).
This distinction is significant because while mass is constant regardless of location, weight can vary with gravitational strength.
For the spring problem, we need to convert mass to weight to understand the force it exerts: \ \( F = mg \).
Here, \( g \), the acceleration due to gravity, is approximately 9.8 m/s\(^2\) on Earth. By multiplying the mass by \( g \), you get the object's weight. For instance, a mass of 1.25 kg has a weight \ (calculated as \( F = 1.25 \, \text{kg} \times 9.8 \, \text{m/s}^2 = 12.25 \, \text{N} \))
that tells us how much force it applies when acting on a spring.
Force Due to Gravity
Gravitational force plays a crucial role in many physical scenarios, especially in our study involving springs and weights. \ It is the attractive force that the Earth exerts on objects, pulling them towards its center.
The force due to gravity is calculated using the equation: \ \( F = mg \),
where \( F \) is the force in Newtons, \( m \) is the mass in kilograms, and \( g \) is the acceleration due to gravity. On Earth, \( g \) is approximately 9.8 m/s\(^2\).
This force is what gives an object its weight, contributing to how much it stretches a spring when suspended.
  • The concept of gravitational force is essential because it enables us to transition between the mass of an object and the force it exerts, which is a critical step in solving problems like calculating spring constants or determining necessary mass for a desired spring displacement.
  • It is this constant presence of gravity that allows us to use consistent equations to calculate the behaviors and interactions of objects both in the classroom and in real-world scenarios.
Understanding gravitational force ensures that students know how to properly link mass to its resulting weight, facilitating a comprehensive grasp of related physics principles.

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

\(\bullet$$\bullet\) A 65.0 -kg parachutist falling vertically at a speed of 6.30 \(\mathrm{m} / \mathrm{s}\) impacts the ground, which brings him to a complete stop in a distance of 0.92 \(\mathrm{m}\) (roughly half of his height). Assuming constant acceleration after his feet first touch the ground, what is the average force exerted on the parachutist by the ground?

\(\bullet$$\bullet\) You push with a horl- zontal fonce of 50 \(\mathrm{N}\) against a 20 \(\mathrm{N}\) box, press- ing it against a rough ver- tical wall to hold it in place, The coefficients of kinetic and static friction between this box and the wall are 0.20 and 0.50 , respectively. (a) Make a free-body diagram of this box. (b) What is the friction force on the box? (c) How hard would you have to press for the box to slide downward with a uni- form speed of 10.5 \(\mathrm{cm} / \mathrm{s}\) ?

\(\bullet$$\bullet\) Atwood's Machine. A 15.0 -kg load of bricks hangs from one end of a rope that passes over a small, frictionless pulley. A 28.0 -kg counterweight is suspended from the other end of the rope, as shown in Fig. 5.60 . The system is released from rest. (a) Draw two free-body diagrams, one for the load of bricks and one for the counterweight. (b) What is the magnitude of the upward acceleration of the load of bricks? (c) What is the ten- sion in the rope while the load is moving? How does the ten- sion compare to the weight of the load of bricks? To the weight of the counterweight?

\(\bullet$$\bullet\) A man pushes on a piano of mass 180 \(\mathrm{kg}\) so that it slides at a constant velocity of 12.0 \(\mathrm{cm} / \mathrm{s}\) down a ramp that is inclined at \(11.0^{\circ}\) above the horizontal. No appreciable friction is acting on the piano. Calculate the magnitude and direction of this push (a) if the man pushes parallel to the incline, (b) if the man pushes the piano up the plane instead, also at 12.0 \(\mathrm{cm} / \mathrm{s}\) paral- lel to the incline, and (c) if the man pushes horizontally, but still with a speed of 12.0 \(\mathrm{cm} / \mathrm{s}\) .

If the toboggan is well waxed so that there is no friction, what force does the sail have to provide to move the student-filled toboggan up the hill at a constant velocity (once it gets started)? \(\begin{array}{l}{\text { A. } g \sin \alpha} \\ {\text { B. } w \sin \alpha} \\\ {\text { C. } w} \\ {\text { D. } w g \sin \alpha}\end{array}\)

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.