Example 1. Compose the equation of the movement of the ball with a mass of T, suspended on the spring, after it was withdrawn from a state of equilibrium (pulled down to the size of U) and left to itself. The mass of the spring and the forces of internal resistance is neglected. From direct experience, it is known that the ball will make fluctuations. Outings will be caused only by elastic power of the spring and are called their own free or independent fluctuations.
