18. A backpack full of books weighing 52.0 N rests on a table in a physics laboratory classroom. A spring with a force constant of 150 N/m is attached to the backpack and pulled horizontally. (a) If the spring is pulled until it stretches 2.00 cm and the pack remains at rest, what is the force of friction exerted on the backpack by the table? (b) Does your answer to part (a) change if the mass of the backpack is doubled? Explain.

College Physics
11th Edition
ISBN:9781305952300
Author:Raymond A. Serway, Chris Vuille
Publisher:Raymond A. Serway, Chris Vuille
Chapter1: Units, Trigonometry. And Vectors
Section: Chapter Questions
Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...
icon
Related questions
icon
Concept explainers
Question

CANNOT BE HAND-DRAWN, YOUR ANSWER WILL BE MARKED AS WRONG IF EXPLANATION IS NOT TYPED

**Problem 18:**

A backpack full of books weighing 52.0 N rests on a table in a physics laboratory classroom. A spring with a force constant of 150 N/m is attached to the backpack and pulled horizontally. 

(a) If the spring is pulled until it stretches 2.00 cm and the pack remains at rest, what is the force of friction exerted on the backpack by the table?

(b) Does your answer to part (a) change if the mass of the backpack is doubled? Explain.

**Solution:** 

1. **Finding the force of friction (part a):**
   - The force exerted by the spring \( (F_{spring}) \) can be calculated using Hooke's Law: \( F_{spring} = k \cdot x \)
     - \( k \) = 150 N/m (force constant of the spring)
     - \( x \) = 2.00 cm = 0.020 m (stretch of the spring)

   \[
   F_{spring} = 150 \, \text{N/m} \times 0.020 \, \text{m} = 3.0 \, \text{N}
   \]

   - Since the backpack is at rest, the force of friction \( (f) \) must balance the spring force: 
   
   \[
   f = 3.0 \, \text{N}
   \]

2. **Effect of doubling the mass of the backpack (part b):**
   - If the mass of the backpack is doubled, its weight will also be doubled. 
   - However, the force of friction in part (a) is only dependent on the force applied by the spring and not the weight of the backpack, given that the backpack remains at rest.

Therefore, the force of friction remains the same (3.0 N) even if the mass of the backpack is doubled.

---

This problem provides insight into the fundamental concept of friction and its independence from mass in certain static scenarios when analyzed under the condition of static equilibrium.
Transcribed Image Text:**Problem 18:** A backpack full of books weighing 52.0 N rests on a table in a physics laboratory classroom. A spring with a force constant of 150 N/m is attached to the backpack and pulled horizontally. (a) If the spring is pulled until it stretches 2.00 cm and the pack remains at rest, what is the force of friction exerted on the backpack by the table? (b) Does your answer to part (a) change if the mass of the backpack is doubled? Explain. **Solution:** 1. **Finding the force of friction (part a):** - The force exerted by the spring \( (F_{spring}) \) can be calculated using Hooke's Law: \( F_{spring} = k \cdot x \) - \( k \) = 150 N/m (force constant of the spring) - \( x \) = 2.00 cm = 0.020 m (stretch of the spring) \[ F_{spring} = 150 \, \text{N/m} \times 0.020 \, \text{m} = 3.0 \, \text{N} \] - Since the backpack is at rest, the force of friction \( (f) \) must balance the spring force: \[ f = 3.0 \, \text{N} \] 2. **Effect of doubling the mass of the backpack (part b):** - If the mass of the backpack is doubled, its weight will also be doubled. - However, the force of friction in part (a) is only dependent on the force applied by the spring and not the weight of the backpack, given that the backpack remains at rest. Therefore, the force of friction remains the same (3.0 N) even if the mass of the backpack is doubled. --- This problem provides insight into the fundamental concept of friction and its independence from mass in certain static scenarios when analyzed under the condition of static equilibrium.
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 4 steps

Blurred answer
Knowledge Booster
Potential energy
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, physics and related others by exploring similar questions and additional content below.
Recommended textbooks for you
College Physics
College Physics
Physics
ISBN:
9781305952300
Author:
Raymond A. Serway, Chris Vuille
Publisher:
Cengage Learning
University Physics (14th Edition)
University Physics (14th Edition)
Physics
ISBN:
9780133969290
Author:
Hugh D. Young, Roger A. Freedman
Publisher:
PEARSON
Introduction To Quantum Mechanics
Introduction To Quantum Mechanics
Physics
ISBN:
9781107189638
Author:
Griffiths, David J., Schroeter, Darrell F.
Publisher:
Cambridge University Press
Physics for Scientists and Engineers
Physics for Scientists and Engineers
Physics
ISBN:
9781337553278
Author:
Raymond A. Serway, John W. Jewett
Publisher:
Cengage Learning
Lecture- Tutorials for Introductory Astronomy
Lecture- Tutorials for Introductory Astronomy
Physics
ISBN:
9780321820464
Author:
Edward E. Prather, Tim P. Slater, Jeff P. Adams, Gina Brissenden
Publisher:
Addison-Wesley
College Physics: A Strategic Approach (4th Editio…
College Physics: A Strategic Approach (4th Editio…
Physics
ISBN:
9780134609034
Author:
Randall D. Knight (Professor Emeritus), Brian Jones, Stuart Field
Publisher:
PEARSON