Why Are Trampolines Bouncier When Wet? (Scientifically) Answered

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In life there are many unanswered questions.

How did the Universe really start? What happens when we die? If God exists and he invented humans then who created God?

But most importantly of all…

Why are trampolines bouncier when they are wet?!

And it is that which we are going to try and answer today.

So without further ado, let’s get started…

Why Are Trampolines Bouncier When Wet?

When a trampoline mat gets wet it becomes heavier and this extra force stretches the springs that hold it in place a bit more. Then you add further weight by jumping on it. This means more force is being used to stretch the springs, but the same mass gets launched so it goes higher and the trampoline is, in effect, bouncier.

As a kid I definitely remember going on a trampoline after a rainstorm and finding it more fun.

Whether that was because there was something a bit more exciting about jumping up and down on a saturated trampoline, or whether it was more than that, I didn’t know at the time.

It turns out trampolines are bouncier when they are wet, and there is a proper scientific explanation behind it.

And I am going to try my best to explain how it works.

Disclaimer: I am by no means a scientist, so bear with me on this!

It Is All About the Extra Weight

The crux of why trampolines are bouncier when they are wet comes down to the rain adding extra weight and making the trampoline mat heavier.

That means before you even get on the trampoline the rain saturated in the mat means the springs have more tension placed on them than if the mat was dry.

So when you add your weight by jumping on the trampoline, more force is used to stretch the springs but less mass gets launched, so the springs propel you higher, ie:

  • Dry trampoline
    Force used to stretch the springs: Your body weight
    Mass launched: Your body weight.
  • Wet trampoline
    Force used to stretch the springs: Your body weight and the weight of the rain.
    Mass launched: Your body weight (and the water temporarily is also released from the fabric).

Extra force is used to stretch the springs, but the same weight is launched so naturally you will be propelled a bit further.

To try and simplify it further, imagine a dry trampoline as a spring with a hook on the end. You then add a weight to the hook (the act of you jumping on the trampoline).

The weight stretches the spring down before it recoils slightly, and will bob up and down for a while before settling back into its natural starting position.

But in the case of a wet trampoline, you are starting with weight on the spring already (the water soaked into the trampoline).

The spring then gets pulled down ever further (you jumping on the trampoline), and then the weight comes off (you and some water are temporarily released).

Because of this extra weight, you get launched higher into the air.

Slippery When Wet

Hand holding water hose

That said, you really shouldn’t be going on a trampoline when it is wet.

Obviously when the polypropylene surface of a trampoline has been saturated with rain it naturally becomes much slicker and more slippery.

Jumping on a wet trampoline means there is more chance of you falling over on it and injuring yourself.

You will notice that pretty much all trampoline manufacturers advise against you using their products when they are wet for this very reason.

Final Thoughts

INFOGRAPHIC Answering the Question Why Are Trampolines Bouncier When Wet
Click infographic to enlarge.

So trampolines are bouncier when they are wet and it is all to do with the rain creating extra force on the trampoline.

When a trampoline mat becomes saturated by rain, the extra weight adds more tension to the springs than if it were dry.

So the water and your body weight are stretching the springs when you jump on the trampoline.

More force is then exerted by the springs when the mat tenses back up, but less mass is launched, so you go higher.

I hope this makes sense.

The bottom line is though that you really shouldn’t be using a trampoline when it is wet as it is more dangerous and most manufacturers recommend against it.

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