6. A horizontal circular disk rotates freely about a vertical axis through its center. It has a mass of 100 kg and a radius of 2.0 m. A person of mass 60 kg stands at the edge of the disk while the disk is rotating at 2.0 rad/s. The person slowly walks from the edge toward the center of the disk. What is the angular speed of the system when the person is 0.50 m from the center?

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
Question

Please do the algebra to show how the answer is 4.1 rad/s

**Physics Problem: Rotational Motion**

---

**Problem Statement:**

A horizontal circular disk rotates freely about a vertical axis through its center. It has a mass of 100 kg and a radius of 2.0 m. A person of mass 60 kg stands at the edge of the disk while the disk is rotating at 2.0 rad/s. The person slowly walks from the edge toward the center of the disk. What is the angular speed of the system when the person is 0.50 m from the center?

---

**Given:**

- Mass of the disk \( M = 100 \, \text{kg} \)
- Mass of the person \( m = 60 \, \text{kg} \)
- Radius of the disk \( R = 2.0 \, \text{m} \)
- Initial angular velocity \( \omega_0 = 2.0 \, \text{rad/s} \)
- Final distance of the person from the center \( r = 0.50 \, \text{m} \)

---

**Equations:**

1. **Conservation of Angular Momentum:** 
   \[ L = I \omega \]

2. **Moment of Inertia for Disk and Person:**
   \[ I = I_{\text{disk}} + I_{\text{person}} \]

3. **Initial Angular Momentum:** 
   \[ I_{\text{disk}} = \frac{1}{2} MR^2 \]  
   \[ I_{\text{person}} = mr^2 \]

4. **Final Angular Momentum:**
   \[ I_o \omega_o = I_f \omega_f \]

---

**Solution Steps:**

- **Initial Moment of Inertia:**
  \[ I_o = \frac{1}{2} MR^2 + mR^2 \]

- **Equation Substitution:**
  \[ \left(\frac{1}{2} \cdot 100 \cdot 2^2 + 60 \cdot 2^2\right) \cdot 2 = \left(\frac{1}{2} \cdot 100 \cdot 2^2 + 60 \cdot (0.5)^2\right) \cdot \omega_f \]

- **Inserting Numbers and Solving for Final Angular Speed \( \omega_f \):
Transcribed Image Text:**Physics Problem: Rotational Motion** --- **Problem Statement:** A horizontal circular disk rotates freely about a vertical axis through its center. It has a mass of 100 kg and a radius of 2.0 m. A person of mass 60 kg stands at the edge of the disk while the disk is rotating at 2.0 rad/s. The person slowly walks from the edge toward the center of the disk. What is the angular speed of the system when the person is 0.50 m from the center? --- **Given:** - Mass of the disk \( M = 100 \, \text{kg} \) - Mass of the person \( m = 60 \, \text{kg} \) - Radius of the disk \( R = 2.0 \, \text{m} \) - Initial angular velocity \( \omega_0 = 2.0 \, \text{rad/s} \) - Final distance of the person from the center \( r = 0.50 \, \text{m} \) --- **Equations:** 1. **Conservation of Angular Momentum:** \[ L = I \omega \] 2. **Moment of Inertia for Disk and Person:** \[ I = I_{\text{disk}} + I_{\text{person}} \] 3. **Initial Angular Momentum:** \[ I_{\text{disk}} = \frac{1}{2} MR^2 \] \[ I_{\text{person}} = mr^2 \] 4. **Final Angular Momentum:** \[ I_o \omega_o = I_f \omega_f \] --- **Solution Steps:** - **Initial Moment of Inertia:** \[ I_o = \frac{1}{2} MR^2 + mR^2 \] - **Equation Substitution:** \[ \left(\frac{1}{2} \cdot 100 \cdot 2^2 + 60 \cdot 2^2\right) \cdot 2 = \left(\frac{1}{2} \cdot 100 \cdot 2^2 + 60 \cdot (0.5)^2\right) \cdot \omega_f \] - **Inserting Numbers and Solving for Final Angular Speed \( \omega_f \):
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 4 steps

Blurred answer
Knowledge Booster
Vector basics
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.
Similar questions
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