An experience that shows how the speed of the body changes when an obstacle occurs is the experience with the cart described in the textbook. This experience undergoes three stages: when a pile of sand is poured, when the sand is leveled, and finally, when it is completely absent. Under these various conditions, the trolley changes its speed differently.
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.