Swimming is a fascinating application of physics principles. When a person swims, they interact with water through multiple forces. Buoyancy keeps them afloat, propulsion moves them forward, while drag opposes their motion. Understanding these forces helps explain how swimmers can move efficiently through water.
Buoyancy is the key force that allows swimming. According to Archimedes' principle, when a swimmer enters water, they displace a volume of water equal to their submerged body volume. The buoyant force equals the weight of this displaced water. Since human body density is very close to water density, the buoyant force nearly balances the swimmer's weight, making floating possible with minimal effort.
Propulsion in swimming is explained by Newton's third law of motion. When a swimmer pushes water backward with their hands and feet, the water exerts an equal and opposite force that pushes the swimmer forward. This action-reaction pair is the fundamental mechanism that allows swimmers to move through water. The more effectively a swimmer can push water backward, the greater the forward propulsive force they generate.