Name: How can rollercoasters hold SO MUCH weight?! | The Secret Genius of Modern Life - BBC
Uploaded: 2025-04-28T21:01:30.000Z
Duration: 3 min 2 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Welcome to the theme park strongman with a difference.

Adverbs of degree

When it comes to designing a track, you need to find a material that can be smooth enough that people aren't rattling around as they're riding your roller coaster.

But strong and sturdy enough to be able to sustain the weight of all of those trains hurtling around at 80 miles an hour.

And so, a good candidate for all of this is steel.

Now here, I have a half kilo block of steel that someone very kind has rolled out into a steel rod for me.

This is just a a cylinder of steel essentially.

So, if this solid cylinder is my roller coaster track, let's see what happens when I add a heavy carriage and load it with passengers.

So we've got 1 kilo on there at the moment.

The rod is already sagging by 2 centimeters.

No one wants a droopy roller coaster, do they?

That solid steel rod has quite a bend, it's just a bit too flexible.

Now let's see what happens when I run the same experiment with the same amount of steel, only this time, my steel rod is hollow.

Last time, my solid steel rod had a 2 centimeter bend.

But now look at the hollow tube, barely 2 millimeters.

Now how can it be possible that you take the exact same materials and run the same experiment and get different results?

Well, it turns out that that tube makes a gigantic difference.

With the hollow tube, there is the same amount of steel, but you've basically taken some from the middle and put it around the outside, increasing the overall surface area.

Which means that when you add a vertical force on it, it is able to distribute that weight all around the surface.

Meaning that physics is basically giving you a free bit of extra sturdiness here.

At 27 kilos, the hollow tube gives barely 1 centimeter of bend compared to our whopping 5 centimeter sag from the solid rod.

Which is, for 27 kilos, a gigantic difference.

Especially when you consider that these trains weigh tons.

And if you scale this whole thing up to the size of the roller coaster, you can just imagine the gigantic difference that tubular steel will make.