What is the Angular Velocity of a Pivoting Rod with a Rigidly Attached Weight?

  • Thread starter Thread starter jhson114
  • Start date Start date
  • Tags Tags
    Center Rod
Click For Summary
SUMMARY

The discussion focuses on calculating the angular velocity of a pivoting rod with a rigidly attached weight. The system consists of a uniform rod of length L = 4 m and mass mrod = 12.4 kg, with a weight of mass M = 5.15 kg attached at one end. The rod is released from a 37° angle, resulting in an angular acceleration of 2.17 rad/s². Energy conservation principles are applied to determine that the change in potential energy of the weight contributes to the kinetic energy when the rod is vertical, while the potential energy of the rod remains unchanged due to its pivot point being at the center of mass.

PREREQUISITES
  • Understanding of angular motion and angular acceleration
  • Familiarity with energy conservation principles in physics
  • Knowledge of potential energy calculations for rigid bodies
  • Basic grasp of rotational dynamics and moment of inertia
NEXT STEPS
  • Study the principles of energy conservation in rotational systems
  • Learn about calculating moment of inertia for composite bodies
  • Explore the relationship between angular acceleration and angular velocity
  • Investigate the effects of pivot points on potential energy changes
USEFUL FOR

Physics students, educators, and anyone interested in understanding the dynamics of pivoting systems and energy conservation in rotational motion.

jhson114
Messages
82
Reaction score
0
https://tychosrv-s.phys.washington.edu/cgi/courses/shell/common/showme.pl?courses/phys121/spring05/homework/08/pivoting_rod_RSD/1.gif

A uniform rod is pivoted at its center and a small weight of mass M = 5.15 kg is rigidly attached to one end. The rod has length L = 4 m and mass mrod = 12.4 kg. The system is released from rest at the q = 37° angle. The angular acceleration just after it is released is 2.17rad/s^2. What is the angular velocity when the rod is vertical?

To do this, you can use the energy conservation. Change in potential energy of the rod plus the change in potential energy of the weight equals the kinetic energy. KE = (1/2)IW^2 = delta total Potentional energy. You get the change in potential energy by finding the delta PE of weight and the rod. delta PE of weight is simply M*G*(change in Height), but how do you find the change in PE of the rod?
 
Last edited by a moderator:
Physics news on Phys.org
jhson114 said:
https://tychosrv-s.phys.washington.edu/cgi/courses/shell/common/showme.pl?courses/phys121/spring05/homework/08/pivoting_rod_RSD/1.gif

A uniform rod is pivoted at its center and a small weight of mass M = 5.15 kg is rigidly attached to one end. The rod has length L = 4 m and mass mrod = 12.4 kg. The system is released from rest at the q = 37° angle. The angular acceleration just after it is released is 2.17rad/s^2. What is the angular velocity when the rod is vertical?

To do this, you can use the energy conservation. Change in potential energy of the rod plus the change in potential energy of the weight equals the kinetic energy. KE = (1/2)IW^2 = delta total Potentional energy. You get the change in potential energy by finding the delta PE of weight and the rod. delta PE of weight is simply M*G*(change in Height), but how do you find the change in PE of the rod?

The potential energy of the rod does not change because the pivot point is the center of mass.
 
Last edited by a moderator:
thats what i thought too. i wasnt getting the right answer, but i guess i did the calculations wrong. thanks !
 

Similar threads

  • · Replies 8 ·
Replies
8
Views
5K
  • · Replies 4 ·
Replies
4
Views
3K
Replies
1
Views
2K
  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 15 ·
Replies
15
Views
4K
  • · Replies 13 ·
Replies
13
Views
3K
  • · Replies 1 ·
Replies
1
Views
5K
Replies
5
Views
3K
Replies
10
Views
3K