In order to get the relationship between angular momentum and angular impulse, we first must look at Newton's 2nd Law. You may already be familiar with Newton's 2nd law as net force equals mass (m) times acceleration (a). What you might not know is that this is for translational motion, movement from one point to another. We can also get a version of Newton's 2nd law for rotational motion. To get this, we have to first define moment of inertia and angular acceleration.
Moment of inertia is a measurement of an object's ability to resist angular acceleration. An object's moment of inertia is dependent on its shape and how it is rotating. Angular acceleration is a change in angular velocity (omega) divided by a change in time. Using these three quantities, we get Newton's 2nd Law for rotational motion to be net torque equals moment of inertia (I) times angular acceleration (alpha).