Question Detail
Question
A circular grinding disk of radius 0.6 m and mass 90 kg is rotating at 460 rev/min. What physical quantity must be calculated to determine the tangential force required to stop the disk in 20 s?
Correct Answer
Option B is the correct answer.
Detailed Explanation
To find the force needed to stop the disk, one must first determine the required angular acceleration (or deceleration). Using the initial angular velocity and the time to stop, the angular acceleration α can be calculated. Then, using τ = Iα, the torque can be found, and finally the tangential force F from τ = F × r.
Hint
The problem involves a change in angular velocity over time, which points to angular acceleration.