Angular Impulse (College Board AP® Physics 1: Algebra-Based): Revision Note

Angular impulse

• The change in an object’s motion due to an external torque acting on it for a time is described by angular impulse

  • This is analogous to linear impulse

• Angular impulse is defined as the product of the average torque exerted on an object or rigid system and the time interval during which it acts

$\mathrm{angular}\mathrm{impulse}=\tau ∆t$

• Where:

  • angular impulse is measured in $\mathrm{N}·\mathrm{m}·\mathrm{s}$

  • $\tau$ = average torque exerted, measured in $\mathrm{N}·\mathrm{m}$

  • $∆t$ = time interval over which the torque acts, measured in $\mathrm{s}$

• Angular impulse has the same direction as the net torque exerted on the object or system

• Therefore, when the average torque exerted over a time interval is zero $\left(\tau =0\right)$, no angular impulse is exerted on the system