Chapter 9 Rotational Dynamics And Precession Flashcards
When does precession occur
When an unbalanced torque acts on the object
What is precession
The circular motion exhibited by the axis of a rotating object
In order for precession to
Occur where must the applied torque be
Must act PERPENDICULAR to the angular momentum direction
How does precession happen
Unbalanced torque always causes a change in momentum
What happens when the torque is applied to an object not spinning initially
Since the object is not spinning initially, it has no angular momentum
The applied torque therefore gives the object momentum
The object rotates in the direction of the torque
What is true if the object already has angular momentum
The direction of the momentum is parallel to the rotation axis of the object
What does the torque applied perpendicular to the rotation axis do?
Changes direction of the angular momentum, causing the axis of rotation to draw a circle in space
The momentum direction continuously changes in a circular path
What is precession analogous to
Centripetal force changing direction of an objects velocity in a circular pattern
The torque does not cause momentum to increase or decrease, just to change direction
When does precession not occur?
If there is no unbalanced torque acting upon the object
The rotation axis of the object is remaining stationary
When does angular acceleration occur
When there is a changing angular velocity
For the non kinematic rotational equations what units must omega (w) be in
Rad/s
For the non kinematic rotational equations what must alpha (a) be in?
Rad/s^2
What is the moment of inertia of a body?
Measure of the “rotational heaviness” of an object
What does the moment of inertia depend on?
The location and orientation of the axis relative to the particles that make up the object
For the non kinematic rotational equations what must theta be expressed in
Rad
