Math Problem Statement
Assuming that a 3 kg disk is initially at rest and a force of F = 69 N is applied to the thin, inextensible cable wrapped round the disk diameter d = 167 mm. Find the angular velocity of the disk after it has turned through 7.6 revolutions. [Answer in rad / s]
Solution
We are tasked with finding the angular velocity of a disk after a force is applied. Let’s break this into steps.
Given:
- Mass of the disk, :
- Force applied, :
- Diameter of the disk, :
- Radius of the disk, :
- Revolutions turned, :
- Moment of inertia of the disk, :
- Convert revolutions to radians:
We are solving for the angular velocity in rad/s.
Step 1: Calculate torque
The torque applied by the force is:
Step 2: Angular acceleration
The angular acceleration is given by: Substitute :
Step 3: Final angular velocity
Using the rotational kinematic equation: where (initial angular velocity), we have: Simplify:
Final Answer:
The angular velocity of the disk is approximately:
Do you need detailed clarifications or explanations for any of the steps?
Here are 5 related questions:
- How does the torque formula change if the force is applied at an angle?
- What happens if the disk is hollow instead of solid?
- Can we calculate the time taken for the disk to reach this angular velocity?
- How is this analysis different if the disk rolls without slipping?
- How would the result change if the force increases?
Tip: Always check unit conversions (e.g., mm to meters) carefully to avoid calculation errors.
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Math Problem Analysis
Mathematical Concepts
Rotational Dynamics
Kinematics
Torque
Angular Acceleration
Formulas
Torque: \( \tau = F \cdot r \)
Moment of Inertia for a Solid Disk: \( I = \frac{1}{2} m r^2 \)
Angular Kinematic Equation: \( \omega^2 = \omega_0^2 + 2 \alpha \theta \)
Theorems
Newton's Second Law for Rotation
Suitable Grade Level
Undergraduate Physics or Advanced High School (Grades 11-12)
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