Required Mathematical Intelligence

Chapter 121 How many meters did the team go
A 110-meter-long team moves at a speed of 1.5 meters per second, and a team member walks from the end of the team to the head of the team at a speed of 4 meters per second.Then immediately return to the end of the line at the same speed, and ask the team how many meters did the team travel from leaving the end of the line to returning to the end of the line?Try to change the above question into a question of finding the length of the team and answer it.

[答案：以队列为参照系，则队员从队尾走到队首速度为4-1.5=3.5m/s，从队首走到队尾用4 1.5=5.5m/s。

The time it takes for a player to leave the tail of the team and return to the tail is t=110/3.5 110/5.5.
Taking the ground as the reference system, the team's forward distance = 1.5t = 77.14m.

Find the length of the queue instead:
Knowing that the team advances s within this time, and knowing the speed of the team relative to the ground, the time for the team to advance can be obtained.Taking the team as the frame of reference, the forward and returning speeds of the team members are known. According to the ratio of these two speeds, the time ratio can be known (because the forward and returning displacements are the same), so the forward and returning time can be obtained, and then the queue can be calculated length. ]
(End of this chapter)