Final answer:
Divers control their rotation by changing their body shape, affecting their moment of inertia and angular velocity, while their angular momentum remains constant during the dive due to the conservation of angular momentum.
Step-by-step explanation:
The impulse during the recoil in springboard diving determines the angular momentum of the diver. When divers pull their limbs in and curl up their bodies during flips, they reduce their moment of inertia, which in turn increases their angular velocity. Conversely, when they extend their limbs just before entering the water, their moment of inertia increases, causing their angular velocity to decrease. However, their angular momentum remains constant during the flight phase because there are no external torques acting on the diver, as per the conservation of angular momentum.
For competitive divers, curling up into a tight ball allows them to spin more quickly and complete the required somersaults or twists before entry into the water. Extending the limbs slows the rotation, allowing for precise control over the entry angle and reducing splash. This practice is crucial for achieving high scores in diving competitions.
In summary, the action of curling up or extending limbs has an inverse effect on angular velocities due to changes in the moment of inertia, while the angular momentum remains constant during the dive. Understanding the effects of body positioning on rotation is critical for a diver's performance.