When two objects collide the total momentum before the collision is equal to the total momentum after the collision (in the absence of external forces). This is the law of conservation of momentum.

Conservation of momentum explains why a gun or cannon recoils backwards when it is fired. When a cannon is fired, the cannon ball gains forward momentum and the cannon gains backward momentum.

From your equations in Steps 2 and 3, solve for angular velocity of the disk at time 2 and the reactions at O.

Researchers have experimentally demonstrated a quantum tornado. Electrons form vortices in the momentum space of the quantum semi-metal tantalum arsenide. A team of researchers from Würzburg has ...