Nails are driven into the corners of a small board. First, the nails driven into the board are set up on the sand with the points pointed up and a weight placed on the board. In this case, the nail heads are slightly pressed into the sand. And then the board is turned upside down, in this case, the nails go much deeper into the sand. This is because the area of the support has become smaller, and the force acting on the board has been preserved.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.