Tangential acceleration is defined as the rate of change of the tangential velocity of a particle in a circular orbit. There are 3 possible values for tangential acceleration. First is when the magnitude of the velocity vector increases with time, tangential acceleration is greater than zero. Second is when the magnitude of the velocity vector decreases with time, tangential acceleration is less than zero. The third possibility is when the magnitude of the velocity vector remains constant, the tangential acceleration is equal to zero.