In the absence of forces, motion in a straight line and constant velocity continues indefinitely. Motion in a circle, however, requires forces to act. ... Since its velocity v equals the distance it moves in one second, one finds . ... The above result suggests that steady motion around a circle, at least for a short time span, can be viewed as the sum of a straight-line motion with fixed velocity v , plus an accelerated motion towards the center of attraction, with the above acceleration, a . ...