3. A hook in boxing primarily involves horizontal flexion of the shoulder while maintaining a constant angle at the elbow. During this punch, the horizontal flexor muscles of the shoulder contract and shorten at an average speed of 70 cm/s. The shoulder muscle insertion moves through an arc length of 2.5 cm during the hook, while the fist moves through an are length of 80 cm. What is the average speed of the fist during the hook? (10 points)