This model illustrates the concept of transformations of energy that occurs during free oscillations of a body under the influence of a quasi-elastic force. The potential energy of the body is proportional to the square of its displacement from the state of equilibrium: U=Ax2, where A > 0 is the coefficient of proportionality. In the case of oscillations of a weight on a spring, A = k/2, Where k is the elastic constant of the spring. Modify the mass of the body m, the value of A, and the total energy of the system E = K + U, and observe the ensuing changes. The relation between the potential and the kinetic energies in the oscillations at any given point in time is represented graphically. Note that in the absence of damping effect, the total energy of the oscillating system remains constant. The potential energy reaches its maximum at the maximal displacement of the body from the state of equilibrium, and the kinetic energy reaches its maximum when the body passes through the state of equilibrium.