This simulation demonstrates relation between the changes in the potential energy of a particle at various positions and particle motion characteristics. You can choose rectangular or harmonic potential type and specify needed constants by sliders: E for total particle energy, coefficient k for harmonic diagram type and U_{1}, a, b for rectangular diagram type. Check boxes U, E, K allow the graphics of potential energy, total energy and kinetic energy of particle correspondently to do visible or invisible. Remember that in any point of particle traveling the sum of its kinetic and potential energies equal constant value. It is a consequence of the particle´s total energy conservation law. Also in any point of particle traveling its kinetic energy must be always positive by definition. Therefore the positions on axis x, where the total energy E later than potential energy U, are forbidden for particle. To observe the favored particle positions activate the check box ?Strobe?.