Rotation

Rotation

1. Rigid Object

   • Rotational Motion about center of mass
     • Purely Rotational Motion
       • Meaning, All points move in circles whose center is on the axis of rotation
   • Def: A rigid object is an object with a definite shape that does not change
   • Translational Motion of Center of Mass
   • Axis of Rotation
     • Usually assumed the center of mass, the axis of rotation is the axis around which a body rotates

2. Angular Position

   • Angular Position is measured by the angle
     • Radians
       • Radians are the ratio of arc length to radius

3. Angular Velocity

   • Angle traveled per length of time
     • Measured in radians per second or revolutions per second
   • Related to Frequency, which is cycles per second
     • The Period is the time it takes to go one cycle

4. Angular Acceleration

   • The rate of change of angular velocity

5. Torque

   • Rotational force, or the extent to which a force will cause rotation
   • The cross product of the force and the position away from the axis of rotation
     • Distance away from axis of rotation is called the lever arm
     • Only the perpendicular component will create a torque

6. Rotational Inertia

   • Moment of Inertia
     • Parallel Axis theorem

7. Rotational kinetic energy

   • total kinetic energy is the sum of rotational kinetic energy and translational kinetic energy

8. Angular Momentum