Why is the angular velocity and angular acceleration(if the rigid body has some) same for all points on a rigid body?
But this gets that angular velocity of AB=angular velocity of BCTake an angle fixed by three points A, B, C within the body. As the body rotates, the angle ABC must be preserved. So AB and BC must rotate by the same angle. Differentiating, deduce that the angular velocities and accelerations must also be the same.