Angular Kinetics - Angular Momentum and Angular Impulse
ANGULAR MOMENTUM (for a body made up of many segments) ABOUT A GIVEN
AXIS OF ROTATION, is the SUM of the angular momenta of individual segments
Can be CONSERVED OR it can be CHANGED in a SPECIFIC MANNER:
- Whenever GRAVITY is the ONLY acting EXTERNAL FORCE, angular momentum is CONSERVED (ie in all air-borne movements).
- When an external torque DOES ACT, it changes the amount of ANGULAR
MOMENTUM present in a system in a predictable manner.
CHANGE in ANGULAR MOMENTUM depends on:
MAGNITUDE of EXTERNAL TORQUE
DIRECTION of EXTERNAL TORQUE
LENGTH of TIME OVER WHICH TORQUE(S) ACT
Therefore, ANGULAR IMPULSE = t x t = DH
Angular Impulse can be changed SIGNIFICANTLY by a large torque acting over a short time interval OR a by a small torque over a large time interval.