A heavy object is attached to a spring and then it is twirled in a horizontal ciricle. Why does/does not the string stretch and discuss in terms of force that maintains circular motion. My answer is that the string will stretch because in the horizontal circle motion, the acceleration will become less and less until it becomes constant, or zero. In order for the accleration to become less the radius has to increase, so the string will stretch. However, this doesn't really discuss it in terms of circular motion, more centripetal acceleration. Help please.