The time for one complete cycle, a left swing and a right swing, is called the period. The period depends on the length of the pendulum, and also to a slight degree on the amplitude, the width of the pendulum's swing.he period of swing of a simple gravity pendulum depends on its length, the local strength of gravity, and to a small extent on the maximum angle that the pendulum swings away from vertical, Î¸0, called the amplitude.
Compulsory elementary schooling was formally introduced in Sweden in 1842. A process of reform, destined to take many years, began in the 1940's with the aim of expanding compulsory schooling.
After World War Two, compulsory education remained as one of the priorities of the state. By 1978, only 1.2 percent of the Polish population was illiterate. In Poland, compulsory education ends at the age of 18. It usually starts when children are 6 years old and ends after 12 years of learning (usually in a high school). Contemporary Polish law distinguishes between compulsory school (obowiÄzek szkolny) and compulsory education (obowiÄzek nauki).