Divers change their body position in midair while rotating about their center of mass. In one dive, the diver leaves the board with her body nearly straight, then tucks into a somersault position.

Explanation:

As no external torque is applied, then the angular momentum is conserved.

When the diver body is straight its moment of inertia is more and then the body is curl so that the moment of inertia decreases.

Angular momentum is conserved, so as the moment of inertia decreases, the angular velocity increases.

So, teh diver curls its body the angular velocity of the diver increases.

they are non-matter

explanation:

they are non-matter. basically, any type of energy or any abstract concept is an example of something that does not matter. other examples include dreams, magnetism, radio, and hate