Hey, I'm Dianna.

You're watching Physics Girl back in my kitchen.

And today we're going to make a mess.

I've got all kinds of ingredients ready that are definitely not edible.

Let's get started.

OK, first experiment you should definitely try at home is a prism made of Jell-O.

So I've get a laser pointer here.

And if I shine it through this Jell-O, you can see some amazing optical properties of light.

So you can't see the laser beam when it's outside of the Jell-O.

But as soon as I move it across the Jell-O, you're seeing the laser beam because of scattering of light.

The laser beam is scattering off of the individual particles inside the Jell-O and scattering the light back to your eyes.

We can also see the property of reflection.

So you can see in the inside here how the laser beam is reflecting off of the inside surface of the Jell-O.

And if I get it at the right angle, I can get a bunch of internal reflections.

You can actually also use this Jello-O like a prism.

So if you take it and put it in the sunlight, it will split the white sunlight up into the colors of the spectrum.

I actually prefer the laser version though.

You get to see so much more of what's going on.

You know my favorite fact about lasers?

They're the key tool used in detecting gravitational waves.

And if you don't know what gravitational waves are yet, check the card up here.

OK, next experiment.

I'm going to open an aluminum soda can using just a Sharpie.

But first, a quiz.

True or false.

A block of aluminum weighs 100 times more than a block of steel the same size?

Incorrect.

The answer is false.

It's only about three times less.

You must not have been "peeling" it today.

It's too good.

Second question.

True or false.

Australia is the world's leading producer of aluminum.

And the answer is false.

I read that about Australia on a fact website.

And then I fact checked it and found out the real answer is China.

Back to you, Dianna.

Thank you, Dianna.

OK, here's the experiment.

I'm going to need safety goggles for this one.

All right, so you take your Sharpie.

And you hold it really firmly in your hand.

And you press it against the lip of the soda can.

It's got that little groove right there.

So you want to go back and forth, pressing firmly along there.

And eventually what happens if you do that is-- [POP] Ooh!

Ahh!

What was the science?

I forgotten it.

It scared it right out of me.

See how on this pull tab of a soda can, there's a little groove there?

Right there, the aluminum is thinner.

So the material is a little bit weaker there.

And as we rub the Sharpie back and forth across the lip, what you're doing is you're flexing the metal back and forth.

And metals have this property where typically if you bend them back and forth like that, they fatigue and they get weaker and weaker.

So eventually that little groove part gets so weak that it can't hold in the pressure of the can because these cans are pressurized to over atmosphere.

Actually, two to three times atmospheric pressure.

That pressure is all pushing out.

Eventually, it pushes out so hard on that little weak joint and it pops it right open.

OK, on to the next experiment, which also has to do with materials.

I'm going to poke this skewer all the way through this balloon.

What happens usually when you poke a balloon with a skewer?

It pops.

Before we go on, though, here's a little trivia quiz about stretchy materials.

For the stretchiest materials in the world, what is the farthest we've been able to stretch them so that they still recover their original shape?

Is it A, twice their original length, B, 10 times their original length, or C, 50 times their original length?

We'll come back to the quiz in a second.

But first, we're going to learn how to skewer a balloon.

You need to find the magic spots in the balloon.

So take a look through the balloon at a light.

You can see through the sides.

But you can't see through the bottom part near the tie, or the top part.

That's because these parts are thicker.

Just in case... so I go through the bottom.

And I like to twist it a little bit.

I even pinch it a little bit so that it gets even less stress.

Well, we're definitely through because I heard a little air leaking out.

And oh no, let's try this again.

Uh-oh, ah, it went through.

And that's how you skewer a balloon.

I've seen people do this before.

But something that I've never seen anyone try before is to stick the skewer through the sides of the balloon and try to blow it up with the skewer already inside.

[LAUGHS] It very quickly pops.

But if you stick the skewer through the top through that nub-in, it works.

That's because it's easier to tear or rip or break the thinner parts of the balloon just like it's easier to tear one page of a book rather than the entire book.

OK, back to the answer to the quiz.

For the stretchiest materials in the world, what is the farthest we've been able to stretch them so that they still recover their original shape?

Drumroll, and the answer is C. There are materials like elastomeric polysulfide nanocomposites that have elongations of over 5000%.

That means that if you took some of this material a foot in length, you could stretch it to over 50 feet.

And it would come back to the same shape.

That's insane.

It would be like blowing up one of these balloons to over a six-foot diameter.

We actually tried blowing up the balloon as far as we could earlier.

We only got them to about two feet.

[SCREAMS] "Orange" you glad you know that now?

The next experiment involves a balloon and a candle.

Adult supervision required for this one.

Hold the balloon over the candle and it will-- [SCREAMS] Dude, it put the candle right out.

Fun fact about candles.

In the 18th century, many lamps and candles were made from spermicide, which is the oil collected from the head cavity of a sperm whale, which also led to the near extinction of those majestic creatures.

Anyway, if you use a balloon with some water in it, there's only a little bit of water.

But if I hold it above the candle now, if this pops, water is going everywhere.

But I am getting it right on that candle flame.

Second fun fact.

Water can hold 11 times as much heat as gallium.

What that means is if you apply the same amount of heat to the same mass of water and gallium, the gallium will heat up 10 times faster.

So the water in this balloon is sucking up all the heat.

The temperature is not increasing that much.

Oh, dear.

Oh, next experiment.

We have to go into a dark room.

I've got a bunch of Band-Aids in here.

When you rip open Band-Aid wrappers, they glow.

This is so cool.

It's a process called triboluminescence where the process of ripping apart the wrappers strips charges off of the material in the wrappers.

And electrons fly across the air and release light.

It's totally visible.

You have to let your eyes adjust for a while in the dark.

And it works best with certain brands of wrappers.

But it's so cool.

It just wastes all your Band-Aids.

For the next one, we're going to do a really cool experiment with milk and food coloring.

But I've got a twist on this one.

The traditional experiment goes like this.

You take some milk, put it on a plate, and take a little bit of food coloring, put it in the middle of the milk.

OK, now take a Q-tip, dip it in some dish soap, put that right in the center of the food coloring.

Hoo, hoo, hoo, hoo, you get some really, really cool patterns if you keep the soap in there.

Now, this is typically done with milk.

But I wanted to try it with water.

OK, so I'm going to pour some water on the plate.

And I'm going to drop some food coloring in here.

And I have to move quickly because it's going to diffuse fast.

So I got my soap in here.

And I'm going to go ahead and dip it right in the middle.

Hoo, hoo, hoo, so it works.

But it's different because the water moves out in an almost perfect circle.

Whereas with the milk, it moves out in this diamond shape.

And I actually don't know why.

If I can figure out the physics before this video goes up, I will share it with you.

But otherwise, I'm going to leave that mystery to you.

You can also show the same effect with water and pepper.

So I'm going to put some water in the plate, sprinkle in some pepper all over the surface of the water.

Now, I'm going to dip the Q-tip in the soap again.

So cool.

So the reason that this happens is because water has got this surface tension.

It's like springs.

All the molecules are pulling against each other.

When you put soap on the top, soap has these molecules that have hydrophobic and hydrophillic ends.

Hydrophobic, meaning it's scared of water, hydrophillic meaning it likes water.

So the hydrophillic ends stick down toward the water.

They're all orienting themselves that way.

They're also spreading out over the surface because soap is less dense than water.

So it sits on the surface.

So the water's pulling like these springs.

And it's almost like you're sticking springs in the middle that are weaker because soap has a weaker surface tension than water.

So the water is pulling out.

And it pulls the soap, which doesn't hold on as strong.

And it pulls the pepper along with it.

Now, this doesn't just work with soap.

If there's some other substance that is less than some water and will spread over the top of the water in a thin film and has a lower surface tension than water, this should work.

Can you think of anything that fits those criteria?

I tried oil.

Let's check it out.

So I'm actually going to use oregano this time because this pepper has a little bit of oil in it.

So it already affects the surface tension.

I'm just going to sprinkle some oregano and then dip my Q-tip in and touch that to the surface.

So the soap is a lot more effective with this experiment.

But the corn oil definitely works.

I can actually see the edge of the corn oil film where it's reached to the edge of this oregano here.

Science is awesome.

Thank you so much for watching.

I hope you try some of these experiments at home.

And happy physics-ing.

Would you like to phone a bunch of friends?

You still have the option to ask the audience.

Have you ever been to Australia?

Oh, you were born there, huh.

Pear-- [STAMMERING] Can you quit "yam"-mering away?

Come on, I'm rooting for you.

Get it?

It's a root vegetable.

[JEOPARDY THEME] [CLANGING] Mic drop.

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