1. Chapter 8
Rotational Motion

2. Constant Angular Acceleration
 How do I calculate kinematic
equations with constant angular
acceleration?

3. Kinematic Equations
 The equations for motion for constant
angular acceleration are the same as
those for linear motion
 Substitute angular quantities for linear
ones

4. Angular Kinematics

5. Example
A centrifuge rotor is accelerated from
rest to 20,000 rpm in 30s
a) What is its average angular
acceleration?
b) Through how many revolutions has
the centrifuge rotor turned during its
acceleration period, assuming
constant angular acceleration?

6. Rolling Without Slipping


7. Reference Frame
 In a, the wheel is rolling
without slipping
 Point P is instantaneously
at rest
 The center moves with
velocity v
 In b, the reference frame
C, so it is at rest
 Point P is now moving with
velocity -v

8. Example
A bicycle slows down uniformly from vo
= 8.40 m/s to rest over a distance of 115
m. The wheel has a diameter of 68.0
cm. Find:
a) Angular velocity of the wheels at t =
0
b) Total number of revolutions each
wheel rotates before coming to rest
c) the angular acceleration of the
wheel

9. Homework
 Read Sections 8.2 and 8.3
 Do Problems # 15 - 21on page 219