If train a is 225 meters long, 25 meters per second, and train B is 20 meters per second, and the time for the two trains to miss is 9 seconds, how long is train B?

If train a is 225 meters long, 25 meters per second, and train B is 20 meters per second, and the time for the two trains to miss is 9 seconds, how long is train B?

If two cars are wrong, it is a complete process for car a to drive through car B
Suppose car B doesn't move, then the speed relative to car a is 25 + 20m, which is 45m. Then car a walks 45 * 9 in 9s, which is 405m
The length of the whole journey for the tail of car a is 255 + that of car B, then the length of car B is 405-255 and 150m
The formula is (25 + 20) * 9-255

The two trains happen to meet at a certain platform. If train a is 225 meters long, 25 meters per second and train B is 20 meters per second, the wrong time of train a and train B is 9 seconds
How many seconds did it take Xiao Ming on train a to see train B pass?

I figured out four seconds, right?
(modeling on paper)
Set a car as a reference
B speed 25 20 = 45m / S
B car length 45 * 9-225 = 180m
It takes 180 / 45 = 4S for people in car a to see car B pass

For two oncoming trains, the speed of train a is 20 meters per second, and that of train B is 25 meters per second. If the length of train a is 200 meters and that of train B is 160 meters, how many seconds will the two trains miss?

The distance of two wrong trains is equivalent to the length of two a trains and two B trains,
Time required for two trains to go wrong: [2 × (200 + 160)] / (20 + 25) = 16 (seconds)

A and B trains are 116 meters long, 10 meters per second, and B trains are 124 meters long, 14 meters per second

If we take car a as a reference, it will not move, while the speed of car B is 10 + 14 = 24 meters
The distance of car B is 116 + 124 = 240 meters
The time is 240 / 24 = 10 meters. Do you understand?