Final answer:
The two conservative forces are gravitational force and elastic force, which are accounted for by potential energy in energy conservation. The force of water on a swimmer is a nonconservative force. The potential energy of a diving board increases as a swimmer steps on it and is released when the diver jumps off.
Step-by-step explanation:
In physics, the two conservative forces discussed are typically gravitational force and elastic (spring) force. These forces are considered conservative because the work done by them only depends on the initial and final positions, not on the path taken. When dealing with conservation of energy, the energy associated with conservative forces is accounted for in terms of potential energy. For example, gravitational potential energy can be represented as mgh, and the potential energy stored in a spring can be represented as 1/2kx², where m is the mass of the object, g is the acceleration due to gravity, h is the height above a reference point, k is the spring constant, and x is the displacement of the spring from its equilibrium position.
As for the force of water on a swimmer, it is considered a nonconservative force because it is dissipative; it does not store energy that can be fully recovered later. Forces like drag and friction, which include the force of water on a swimmer, convert mechanical energy into other forms like heat, which generally cannot be recovered to perform work in the system.
Regarding the potential energy of a diving board, assuming internal friction is negligible, the potential energy of the board increases as a swimmer steps onto it and depresses the board, storing elastic potential energy. Once the swimmer jumps off and the board springs back to its original position, this stored potential energy is converted back into kinetic energy as the board moves upward. However, after the swimmer's feet leave the board, there is no longer any energy stored in the board.