Finding time in a pulley system

Click For Summary
SUMMARY

The discussion focuses on a physics problem involving a horizontal bar with a mass of 3.2 kg mounted on a spindle, which is subjected to a pulling force of 15.0 N via a string wrapped around the spindle. The system rotates at an angular speed of 5.5 rad/s, and the key question is determining the time it takes for the system to come to a stop after the string unwinds completely. Participants emphasize the need to calculate the frictional torque affecting the system's deceleration, which is crucial for solving the problem.

PREREQUISITES
  • Understanding of rotational dynamics and angular motion
  • Familiarity with torque and its effects on rotational systems
  • Knowledge of frictional forces and their role in motion
  • Ability to apply kinematic equations for rotational motion
NEXT STEPS
  • Calculate the frictional torque acting on the system using the given parameters
  • Learn how to apply the equation Δω=α Δt to find angular deceleration
  • Research the relationship between torque, angular acceleration, and angular velocity
  • Explore the principles of energy conservation in rotational systems
USEFUL FOR

Students studying physics, particularly those focusing on rotational dynamics, as well as educators seeking to enhance their understanding of torque and angular motion concepts.

Axel7
Messages
4
Reaction score
0

Homework Statement


A horizontal bar with a mass of 3.2 kg and a length L of 64 cm is rigidly mounted to a vertical spindle of negligible mass such that the two objects spin together. The spindle has a diameter of 2.0 cm, and it is attached to the bar a distance of L /4 from its centre of mass. A string is wrapped around the spindle, and is pulled with a steady force of 15.0 N. The string is wrapped four times around the spindle.
If the system rotates at an angular speed of 5.5 rad/s when the string unwinds fully and drops from from the spindle, after the string has fully unwound, how long does it take for the system to come to a stop?

Homework Equations

The Attempt at a Solution


I've tried using Δω=α Δt but I don't know what α is? I'm pretty lost on what to do.
 
Physics news on Phys.org
The question implies it will come to a stop. Why would that be, do you think?
 
I'm assuming there is a frictional torque that would cause it to stop, but I don't know how to use that to determine the time.
 
Axel7 said:
I'm assuming there is a frictional torque that would cause it to stop, but I don't know how to use that to determine the time.
There is enough information to deduce the frictional torque.
 

Similar threads

Finding the period of pulley system
  • · Replies 22 ·
Replies
22
Views
3K
Force applied on the pulley of a system
  • · Replies 8 ·
Replies
8
Views
3K
Pulley system, find the acceleration and tension
  • · Replies 40 ·
2
Replies
40
Views
6K
How Does a Lift's Acceleration Affect the Pulley System Dynamics?
  • · Replies 3 ·
Replies
3
Views
2K
What Happens to Angular Acceleration and Moment of Inertia in a Pulley System?
  • · Replies 2 ·
Replies
2
Views
8K
Conservation of Momentum: Pulley System
  • · Replies 4 ·
Replies
4
Views
2K
Question regarding block and pulley system with inertia
  • · Replies 4 ·
Replies
4
Views
2K
How Do You Solve a Complex Energy Pulley Problem?
  • · Replies 9 ·
Replies
9
Views
2K
Block-pulley system and rotational dynamics
  • · Replies 5 ·
Replies
5
Views
5K
How Do You Calculate the Angular Motion of a Pulley System?
  • · Replies 15 ·
Replies
15
Views
2K