Period of oscillations of the disk

Click For Summary
SUMMARY

The period of oscillations for a circular disk of radius R and uniform density, pivoting about a fixed point on its circumference, is calculated using the formula T = 2π√(R/g). The discussion highlights the necessity of applying the parallel axis theorem to determine the new moment of inertia, as the disk does not undergo uniform circular motion due to the changing angular velocity. The key takeaway is the importance of understanding the dynamics involved in the oscillation of the disk rather than assuming uniform motion.

PREREQUISITES
  • Understanding of rotational dynamics and moment of inertia
  • Familiarity with the parallel axis theorem
  • Knowledge of simple harmonic motion principles
  • Basic physics equations related to force and acceleration
NEXT STEPS
  • Study the parallel axis theorem in detail
  • Learn about the moment of inertia for different shapes
  • Explore the principles of simple harmonic motion
  • Investigate the differences between uniform circular motion and oscillatory motion
USEFUL FOR

Physics students, educators, and anyone interested in understanding the dynamics of oscillating systems, particularly in rotational motion scenarios.

cupcake
Messages
73
Reaction score
0

Homework Statement



A circular disk of radius R and uniform density is free to pivot about a fixed point P on its circumference. Calculate the period of oscillations of the disk, in the plane of Figure I, when it is displaced by a small angle about its pivot and released.


Homework Equations



F=ma
a=v^2/R
v=2*R*pi/T

The Attempt at a Solution



F=mv^2/R
mg=mv^2/R
g=v^2/R

where v= 2*R*pi*/T

thus, T= 2*pi*root(R/g)

can anyone advise?
 

Attachments

  • Screen shot 2010-11-19 at PM 08.20.59.png
    Screen shot 2010-11-19 at PM 08.20.59.png
    10.6 KB · Views: 559
Physics news on Phys.org
I am afraid its not correct. You have to calculate the new moment of inertia. Use parallel axis theorem to help you.
 
And the problem here is, this is not a uniform circular motion.

What is the characteristic of a uniform circular motion? And how does it NOT fit into this situation?
 
why this is not a uniform circular motion?
is it because the disk is not moving in constant speed?
 
You are right. Because it is not moving at constant linear velocity. So angular velocity is always changing too, v=rw.
 

Similar threads

Replies
7
Views
3K
  • · Replies 2 ·
Replies
2
Views
897
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
Replies
11
Views
1K
  • · Replies 6 ·
Replies
6
Views
2K
Replies
4
Views
3K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K