Variable speed circular motion

Tangential and normal components of acceleration in non-uniform circular motion

The video below shows an object moving around a circle with variable speed. The object's velocity and acceleration are displayed in blue and red, respectively. The orthogonal decomposition of acceleration into tangential and normal components is shown in light red. Notice that the "full" acceleration vector only points directly at the center of the circular track at moments when its tangential component vanishes. Acceleration makes an acute angle with velocity whenever the object is speeding up, and an obtuse angle whenever the object is slowing down.