Physics 101- Introduction to Mechanics
March 22- Rotational Dynamics

 

 

 

 
 

 

  Dynamics

How do we make things rotate?  Apply a force.  But how we apply that force can make differences in how the object rotates.
 

So, what is the relation between torque and angular acceleration?  Look to linear motion, F= ma.  What quantity plays the role of "mass" in rotation? 

I=Smr2


When talking about rotation where the mass is located is important, not just what is the total mass.  If the mass is close to the rotational axis then object easily rotates, has a small I.

 
For continuous shapes we replace the summation with an integration and you get results seen in table 8-1.
 
 

Newton's Second Law for rotating systems is:

t= I a



Given the following configuration of three masses (at the vertices of a 0.5m, 0.4m, 0.64m right triangle).  Find the moment of inertia through the 1 kg mass.  Then through the 2 kg mass (the axis passing through each).  
 

 
 
 

 

About the Course
Syllabus
Schedule
Study Hints
Problem Solving
Contract
BlackBoard
Homework- assignments & solutions
Miscellaneous links
About Dr. Jeff
Feedback


 
 
 
 
 

 

 
     
Jeff Phillips
phillips@lmu.edu
Loyola Marymount University
Spring 2002