Chapter 8 Rotational Kinematics

Rotation – (rotate) Revolution – (revolve) To move around an external axis. To spin on an internal axis.

The Record Player or Turntable

A penny rotates on the turntable at 45 RPM How fast is the penny moving? Angular Velocity Tangential Velocity (Rotational Speed)(Linear Speed) 45 revolutions/minute or 45 x (2  ) = rad/min Depends on the distance (r) away from the center

Angular Velocity = Rotational Velocity = ω Tangential Velocity = Linear Velocity = v V depends on distance from axis rotation.

What is pi? Pi is the ratio of a circle’s circumference to diameter.

Arc length r = radius s = arc length

What is a radian? A radian is a unit used for measuring angles. Angles can be measured in degrees or radians r = radius s = arc length

Angular Displacement (Δθ) - Can be measured in 1) degrees 2) radians 3) revolutions (1 rev = 360°)

Angular Velocity (ω) - Measured in rad/sec or rev/min (etc)

Angular Acceleration (α) - Measured in rad/sec 2 or rev/min 2 (etc)

ASSIGN: Ch. 8 #2,12,16,32 p. 231 due Friday