Example: 1 a local train, with body length 125m and speed 17m per second. An express train with a body length of140m and a speed of 22m per second. How many seconds does it take for the local train to drive ahead and the express train to catch up from behind? Explanation of train of thought: When the express train catches up with and overtakes the local train, the express train takes the sum of two bus lengths more than the local train, and the express train travels (22- 17) kilometers more than the local train every second, so it is feasible for the express train to catch up with and overtakes the local train. (125+140) ÷ (22-17) = 53 (seconds) A: It takes 53 seconds for the express train to catch up from behind and completely overtake. It took 1 10 seconds for train A to catch up with train B from behind. The length of train A is120m, and the speed of train B is 20m per second. The speed of train B is18m per second. B how long does the train take? (20-18) ×1120 =100 (m) It took 3 1 s for the train 3 A to catch up with the train B from behind, and the length of the train A was/kloc. 25-(150+160) ÷ 31=15 (m) Summary: In overtaking problem, distance difference = long body and overtaking time = long body and ÷ speed difference (2) Wrong car problem (2) How many seconds does it take for two trains to pass by? (220+300) ÷ (10+16) = 20 (seconds)