# ROTATIONAL MECHANICS NOTE BY PLANCESS

An object at rest tends to remain at rest and an object in rotation tends to continue rotating with constant angular velocity unless compelled by a net external torque to act otherwise.

Angular acceleration is directly proportional to net torque and inversely proportional to moment of inertia or
∑Ï„ = IÎ±. For every action there is an equal and opposite reaction. (Here action and reaction refer to torques.) When an object moves in a straight line then the motion is considered as translational but when the same object moves along an axis in a circular path then it is known as Rotational Motion. Consider a wheel rolling without slipping in a straight line. The forward displacement of the wheel is equal to the linear displacement of a point fixed on the rim.

As we know that in linear motion, an object is moved till it feels any external force. This force changes the motion of objects. But when an object is moving about a fixed axis in a circular or curved path then, it can also feel the force better known as Torque. It is easier to open a door by pushing on the edge farthest from the hinges than by pushing in the middle. Thus, the torque is a force which is studied under rotational dynamic.

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