1: Example: Two cars are driving from A and B at the same time, and meet at a distance of 80 km. After meeting, the two cars continue to move forward. When a car arrives at B and B, they immediately return to their original road. When they met at a distance of 60 km for the second time, what was the distance between A and B?
Solution: s = (3s'+s'')/2 = (3x80+60)/2 =150km.
One: cross-strait type: here s' stands for the first meeting, and s'' is the distance from B to the second meeting.
Example: A and B walk in opposite directions at the same time at a constant speed. The first time we met, it was 6 kilometers away from A, and we went on, and returned immediately after we reached the starting point of the other side. The second time we met, it was 3 kilometers away from B. What was the distance between AB and B?
Solution: s = 3s'-s'' = 3x6-3 = 15km.
Extended data:
( 1)? The problem of travel is to study the movement of objects, which is a common problem in mathematics. Travel problem is an application problem that reflects the uniform motion of objects. Travel problems mainly include fairs, meetings, running water, train travel, clocks and watches.
(2) Travel involves many changes, some involving the movement of one object, some involving the movement of two objects, and some involving the movement of three objects. There are three situations involving the movement of two objects: opposite movement (encounter problem), same movement (chase problem) and opposite movement (separation problem).
(3) Whether it is "the movement of one object" or "the movement of two objects", whether it is "the opposite movement", "the same movement" or "the opposite movement", their characteristics are the same. Specifically, they reflect the same quantitative relationship, which can be summarized as: distance = speed × time.
References:
Baidu Encyclopedia-Travel Problem Formula