... Electric Forces . 19.Motion in a Circle . ... In the absence of forces, motion in a straight line and constant velocity continues indefinitely. ... Each rotation the stone covers a distance . ... Since its velocity v equals the distance it moves in one second, one finds . ... while the actual motion brings it to some point D on the circle, whose center will be denoted by O. In the absence of forces, motion in a straight line and constant velocity continues indefinitely. ...