Lesson 5 - Angular Kinematics

Rigid Body

A body that maintains a constant shape

When is a body considered rigid?

The distance between any two points on that body remain fixed

Axis of rotation

a fixed line about which a body rotates

Where do rotations occur?

In a plane, about an axis that is perpendicular to that plane

What plane is perpendicular to sagittal?

Frontal

What plane is perpendicular to frontal?

Sagittal

Clockwise rotations

Negative

Counterclockwise rotations

Positive

Angular position

the orientation of a rigid body in reference to some axis

What is angular position measured in

degrees or radians

Radian

A ratio between an arc length (s) and the radius (r)

Arc length

the length of a curve if you traced a curve with a piece of string, straightned it then measured

Displacement

Distance from the origin

Distance

Distance travelled

Conversion from degrees to radians

Divide the degrees by 57.3

Angular Displacement

The change in orientation of a rigid body in referenced to some axis

ex: change in angular position between two time points of interest

Angular speed

How fast a body is rotating

What quantity is Angular speed?

Scalar quantity

What quantity is Angular velocity?

A vector quantity

Angular velocity

how fast a body is rotating in a particular direction

Angular velocity typical units

deg/sec or rad/sec

Angular acceleration

how quickly a body is speeding up or slowing down its rotation in a particular direction

- time rate of change of angular velocity

What quantity is Angular acceleration?

A vector quantity

Angular acceleration typical units

deg/sec² or rad/sec²