ANYA TAYLOR
We're heading to a town called Gingin, 90km out of Perth, where Derek has something special in store for us.
DR DEREK MULLER
I'm going to show you something you've never seen before in an experiment that combines physics and fruit salad on a massive scale. Oh, check it out!
SIMON PAMPENA
Hey!
DR DEREK MULLER
You see that?
SIMON PAMPENA
There's the tower!
DR DEREK MULLER
This is what we came here for.
SIMON PAMPENA
Oh, my Lord. Look how tall it is!
ANYA TAYLOR
It's pretty big.
DR DEREK MULLER
The Leaning Tower of Gingin is the centrepiece of the Gravity Discovery Centre. This place is incredible. Why did you build it?
BRAD WHITAKER
Well, we built this so that people could throw water balloons off the top.
DR DEREK MULLER
Is that it?
BRAD WHITAKER
Basically to replicate experiments in gravity that Galileo did from the leaning tower of Pisa.
DR DEREK MULLER
But that's a massive structure! I mean, is it worth it building that thing just to drop water balloons off?
BRAD WHITAKER
We think so, yeah. Great fun.
DR DEREK MULLER
You know what, we want to bring it to the next level. We want to drop some watermelons off there. Can we do that?
BRAD WHITAKER
Absolutely. Why not?
DR DEREK MULLER
But first — we need to get all of these up there.
SIMON PAMPENA
Is there a lift up there, Derek?
DR DEREK MULLER
Uh, I don't believe there is. You're gonna run up some stairs with some watermelons.
SIMON PAMPENA
Are we taking this all the way up?
DR DEREK MULLER
All the way, sir.
Simon falls up stairs
SIMON PAMPENA
Oh!
DR DEREK MULLER
Are you alright?
SIMON PAMPENA
(Laughs)
ANYA TAYLOR
Aw, poor Simon.
DR DEREK MULLER
OK, what we're gonna be doing is dropping some watermelons off the top. We're gonna kind of be racing them, seeing which one hits the ground first. Now, that may seem like a pretty basic experiment, but I have a few tricks up my sleeve. Things that people haven't done here before. I think the result might just surprise you.
ANYA TAYLOR
This tower is a vertigo-inducing 45m tall and leans 15 degrees.
DR DEREK MULLER
That gives us a clean drop to the sand below, where Mark, our slow motion expert, and these keen-eyed kids will help analyse the results. So if we were to drop both of these at exactly the same time from the top of that tower, which one is gonna land first?
KIDS
Watermelon.
DR DEREK MULLER
The watermelon?
KIDS
Yeah.
DR DEREK MULLER
Do you have a reasoning behind it?
BOY
If it's light, it won't go as fast.
DR DEREK MULLER
Yeah. What do you know about Galileo?
GIRL
In a movie, he's a bird.
DR DEREK MULLER
Yeah? Well, more than 400 years ago, Galileo the MAN discovered that all falling objects accelerate at the same rate regardless of how heavy or light they are.
ANYA TAYLOR
Subject to wind resistance, of course. So our watermelon and rockmelon should hit the ground at the same time.
DR DEREK MULLER
Check it out, check it out!
Watermelon splats on sand
KIDS
Oh!
DR DEREK MULLER
Seen at 1,500 frames a second… it's clearly not the dead heat we expected.
Melons fall in slow motion
DR DEREK MULLER
I guess what we didn't account for is that, over this distance, air resistance becomes significant. And it has a bigger effect on the rockmelon because it's lighter. Um, can we get two watermelons dropped side by side?
KIDS
Oh, here we go.
ANYA TAYLOR
So, are you all ready?
KIDS
Yes!
SIMON PAMPENA
We can't hear you!
KIDS
YES!
ANYA TAYLOR AND SIMON PAMPENA
Three! Two! One!
BOY
Go!
Watermelons splat on sand
(KIDS SCREAM)
Watermelons fall in slow motion
ANYA TAYLOR
Closer but still no cigar. Our next drop will need to be perfectly synchronised.
DR DEREK MULLER
It has to be. In order to demonstrate that two falling objects can accelerate at very different rates. Now, what we're setting up right here is an experiment that has never been done before at this location, alright? And very few people around the world have ever done this. We're gonna do two watermelons, alright? Two watermelons from the top. But to one of the watermelons, we're gonna attach a chain. The chain is gonna hang down below the watermelon and then it's going to connect up to the railing. The chain is long enough so that it will reach the ground. So, basically, one of these watermelons is going to be like our model bungee jumper who's connected up by a cord to the platform. And then the other watermelon is gonna be like someone who really doesn't need a bungee cord, someone who's just gonna freefall.
SIMON PAMPENA
Bob, it's OK. It'll be quick. It'll be painless. It'll be fun. You're gonna experience gravity.
Simon kisses watermelon
DR DEREK MULLER
Which one do you think is going to hit the ground first? The one that's connected to the chain or the one that's freefalling?
BOY
Freefalling.
DR DEREK MULLER
Freefalling? What do you think?
BOY 2
The chain.
DR DEREK MULLER
The chained one's gonna hit first?
GIRL
I think the freefalling one because, like, the chain will just slow it down.
DR DEREK MULLER
Chain may slow it down a little bit? Well, there's only one way to find out. And that's to actually do it.
ANYA TAYLOR
(Exhales) Easy for you to say.
DR DEREK MULLER
Give me a countdown from up there, please.
ANYA TAYLOR
One, two, three.
Watermelons fall to ground
DR DEREK MULLER
Whoa! That was crazy. That was an amazing synchronised drop.
ANYA TAYLOR
Really?
DR DEREK MULLER
I'm so, so impressed. Man, I gotta hand it to those guys at the top. They dropped them so perfectly. But it's no time for hugs, guys. In slow motion, it's clear we didn't get the result we were expecting. Maybe I should let you in on this. The one that's got the chain attached is meant to land first. It should accelerate actually faster than freefall. This slack at the top invalidated the experiment.
Simon and man release watermelon and chain respectively
DR DEREK MULLER
Two people took the weight of the heavy chain and watermelon and they didn't release simultaneously. But there could be something else at play. When you do this experiment, the theory says that the chain needs to be a lot heavier than the bit at the end. And in this case, we're using watermelons which are really, really heavy, so… We've got a couple of rockmelons here. Maybe if we do the same experiment but using rockmelons, we'll be able to see the difference that we want.
ANYA TAYLOR
We weren't planning on this, and these are our last rockmelons, so we'd better get this right.
SIMON PAMPENA
No pressure, then, Anja.
ANYA TAYLOR
Three, two, one!
(All cheer)DR DEREK MULLER
Beautiful! Look how the chained rockmelon accelerates faster than the freefalling one. It's an awesome result. The key is this bend in the chain.
Chain hangs in parabola beneath rockmelon
DR DEREK MULLER
The chain on the left-hand side is falling, but, as it goes around the bend, it slows down and becomes stationary. So it's accelerating up. The tension required to pull the chain up actually pulls down on the rockmelon, accelerating it at a rate greater than that due to gravity, and that's why it hits the ground first.
Man swings whips
DR DEREK MULLER
It's the same principle that propels the tip of a whip fast enough to smash the sound barrier. The chain does act like a whip on that rockmelon, which pulls it actually faster than it would normally accelerate just under freefall alone. Isn't that incredible?
KIDS
Yeah!
DR DEREK MULLER
Isn't that incredible?
KIDS
YEAH!
SIMON PAMPENA
We did it!
DR DEREK MULLER
Yes! Physics! Simon, I want to kiss you!
ANYA TAYLOR
And, with Derek's dream drop done and dusted, it's time to hand back the tower to the kids.
Kids hold water balloons at top of tower
KIDS
One! Two! Three!
SIMON PAMPENA
Drop!
SIMON
Yay!
Numerous water balloons splat