1, two objects from two places, walking in opposite directions, will inevitably meet on the way after a period of time. This kind of problem is called encounter problem. The question of meeting is face to face.

2. The problem of meeting is to study the relationship between speed, time and distance. It is different from the general travel problem in that it is not the movement of an object, so the speed it studies includes the speed of two objects, that is, the sum of speeds.