Physics Of Diving

University of Virginia physics professor Lou Bloomfield explains how divers use gravity and change their shape to execute the perfect dive. Diving is pretty much “falling with style”, but it is not always easy to be graceful. Once a diver leaves the diving board or platform, Earth’s gravity causes him to fall.

However, the diver has to control his own rotation. The falling diver’s rotation is controlled by his angular momentum, which is the quantity of rotation of a body, which is the product of its moment of inertia and its angular velocity. A key to graceful diving is changing shape in just the right way. The diver begins the dive by stretching out long, then rotating slowly. He must pull into a ball in the middle of the dive so that he rotates quickly. Then, to finish the dive, he must stretch out long again so that when he enters the water, he is barely rotating. The more streamlined his entry into the water, the less he will disturb the water on the surface of the pool, and therefore, the resulting splash will be less pronounced.

He has to adopt an entry shape with his body that allows the water to move smoothly around him with a minimum of resistance. Once he is below the surface, he can spread his body out and slow down to a stop. Hopefully when he comes back up, he will have great scores!