This book has little likeness to a school collection of problems, since in solving many of them items of knowledge from many different divisions of physics may be required. Therefore the author decided to divide the problems into groups according to the situation in which the task is to be performed. In each group the problems are arranged in the order of increasing difficulty, though certainly the author's opinion on the complexity of the problem need not necessarily coincide with the reader's.The book is intended, in the first place, for pupils of "O" level classes, who have already mastered a considerable amount of knowledge in physics, but there are many problems which pupils who only have started to study this wonderful science will be able to cope with. It seems that the book can prove useful to teachers of secondary school, for example, in compiling a questionnaire for a school party devoted to "entertaining physics".