A jump rope is made from an elastic cord with two hollow plastic handles attached to each end. Two boys, instead of using the rope for jumping, decide to use it for a tug-of war. Each boy pulls on an end of the rope. One boy lets go of his handle; the other boy holds his end and is almost immediately struck in the eye by the sharp end of the released handle. Derive an equation for the energy stored in the rope. A force of 9 lb was applied to each handle stretching the rope 10 in. just prior to its release. The rope and handle weighed 2 oz. What was the approximate speed of the handle when it struck the boy's eye?
