Newton's second law for rotational motion?

Answer 1

I am not sure whether Newton actually stated this law... It's more like an analogy, or equivalent. It is still valid, though.

Newton's Second Law for linear movement: force = mass x acceleration.

The equivalent for rotational movement: torque = (moment of inertia) x (angular acceleration).

Keeping it simple: acceleration = change in velocity/time for change. Velocity is a vector having both size and direction, thus any change in direction changes velocity. Not its magnitude, just its direction. A change in velocity with time means the object is accelerating. To do this a force must be applied perpendicular to the direction of the velocity vector to pull the object round into a circle. F=ma applies, therefore.

Answer 2

Newton's second law for rotational motion states that the net torque acting on an object is equal to the product of the object's moment of inertia and its angular acceleration, similar to how force is related to acceleration in linear motion. Mathematically, this can be written as τ = Iα, where τ represents torque, I is the moment of inertia, and α is the angular acceleration.

Answer 3

external net torque = moment of Inertia x angular acceleration