Enlarge image
You have probably cracked a few tough nuts in the past few days.
Fortunately, the following puzzles do not fall into this category.
Hopefully it won't strain your gray matter for too long.
You are standing with a friend on a 380-meter-long platform when an announcement comes: "Caution, train passage".
That makes you curious.
You want to see what you can find out about the train and use the stopwatch.
Your friend stops how long it takes for the train, an ICE, to pass them.
It's 7 seconds.
They stop how long the ICE takes to pass the entire platform.
26 seconds elapse between the moment the head of the train reaches the platform and the moment the end of the train leaves the platform.
How long is the train?
(Note: Do not set up complicated equations with one or more unknowns. Calculate as simply as possible. The speed of the train as it passes is constant.)
The train is
140 meters
long.
26 seconds pass between the Zugspitze reaching the platform and the end of the train leaving the platform.
It takes 7 seconds for the train to pass a fixed point.
Therefore, it takes 26-7 = 19 seconds from reaching the platform to leaving the platform through the Zugspitze.
Because the platform is 380 meters long, the train has a speed of 380 m / 19 s = 20 m / s.
If the passage of the entire train takes 7 seconds, the train must be 7 s * 20 m / s = 140 meters long.
I discovered this puzzle in the book "The Garden of the Sphinx" by Pierre Berloquin.
If you missed a puzzle from the past few weeks, here are the most recent episodes:
The fly in the glass
How big is the yellow rectangle?
The main thing is 1000
Heads or tails
Crazy
How big is the yellow triangle?
Which stick is magnetic?
Who will get the last coin?
Difficult legacy
How big is the circular ring?
