3. Plan for Today (AP Physics 2)
C Testers
Angular Motion Review – discuss and example problems
B Testers
Magnetism Free Response Problems (Individually)

4. Reminder
Centripetal acceleration:

5. Reminder - Momentum

6. More Momentum

7. Rotational Displacement, 
Consider a disk that rotates from A to B: B
Angular displacement q:  A
Measured in revolutions, degrees, or radians.
1 rev = = 2 rad
The best measure for rotation of rigid bodies is the radian.

8. Definition of the Radian
One radian is the angle  subtended at the center of a circle by an arc length s equal to the radius R of the circle. s
1 rad = = 57.30 R

9. Angular Velocity
Angular velocity,w, is the rate of change in angular displacement. (radians per second.)
w = Angular velocity in rad/s. q t
Angular velocity can also be given as the frequency of revolution, f (rev/s or rpm):
w = 2pf Angular frequency f (rev/s).

10. Angular Acceleration
Angular acceleration is the rate of change in angular velocity. (Radians per sec per sec.)
The angular acceleration can also be found from the change in frequency, as follows:

11. Angular and Linear Speed
From the definition of angular displacement:
s = q R Linear vs. angular displacement
v = w R
Linear speed = angular speed x radius

12. Angular and Linear Acceleration:
From the velocity relationship we have:
v = wR Linear vs. angular velocity
a = aR
Linear accel. = angular accel. x radius

13. Angular vs. Linear Parameters
Recall the definition of linear acceleration a from kinematics.
But, a = aR and v = wR, so that we may write:
becomes
Angular acceleration is the time rate of change in angular velocity.

14. A Comparison: Linear vs. Angular

15. Problem Solving Strategy:
Draw and label sketch of problem.
Indicate + direction of rotation.
List givens and state what is to be found.
Given: ____, _____, _____ (q,wo,wf,a,t)
Find: ____, _____
Select equation containing one and not the other of the unknown quantities, and solve for the unknown.

16. Summary of Formulas for Rotation

17. Moment of Inertia Rotational inertia
Rotational analog to mass for linear motion

20. Work on Review Materials