In the preceding two chapters we studied situations that are complex to analyze with Newton’s laws. We were able to solve problems involving these situations by apply in a conservation principle—conservation of energy. Consider another situation—a60-kg archer stands on frictionless ice and fires a 0.50-kg arrow horizontally at 50 m/s. From Newton’s third law, we know that the force that the bow exerts on the arrow will be matched by a force in the opposite direction on the bow (and the archer). This willcause the archer to begin to slide backward on the ice. But with what speed? We can-not answer this question directly using either Newton’s second law or an energyapproach—there is not enough information.