Angular Kinematics & Kinetics

Angular Kinematics

Linear kinematics has an angular counterpart

• Linear

  • position

  • displacement

  • velocity

  • acceleration

  • force

  • mass

• Angular

  • angular position

  • angular displacement

  • angular velocity

  • angular acceleration

  • torque

  • moment of inertia

Angular position

• location around the axis of rotation relative to some reference location

  • measured in radians or degrees

• axis of rotation = joint

• reference location (0º) is wherever we want

  • but we need to pick 0º carefully so that it makes sense for our movement

Angular Displacement

• final joint position- initial joint position = angular displacement

Angular Velocity

change in displacement over time

final disp. -initial disp. / time = angular velocity

Angular Acceleration

change in velocity over time

final velocity - initial velocity /time

Angular Kinetics

• Linear kinetics : torque = moment of inertia x angular acceleration

  • T= F x r

    • moment arm is the perpendicular distance from axis to point of application

• Angular kinetics: ∑t=ia

  • sum of torque = moment of inertia x angular acceleration

    • it matters where mass is compared to axis of rotation (ex spinning a barbell horizontally vs vertically)