Linear Momentum and Its Conservation
In the preceding two chapters we studied situations that are complex to analyze with Newton’s laws. We were able to solve to solve problems involving these situations by applying a conservation principle-conservation of energy. Consider another situation-a 60 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 will cause the archer to begin to slide backward on the ice. But with what speed? We cannot answer this question directly using either Newton’s second law or an energy approach-there is not enough information.