While a book is stationary on a table, the weight ball is working vertically down on the book, and according to Newton's third law, the table is applying the same amount of upward force F on the book . Since the values of these two balls are equal and opposite, the value obtained is called value. In other words, the force of equality is acting on the book. The reason is that we know that if the values of two balls acting on an object are equal and the directions are opposite, then they are called equilibrium.