Imploding Drum
Today I'm at the University of Sydney with Dr. Phil, and we're talking about the pressure that all of us are under. You are under a lot of pressure, probably 10,000 kg. 10,000 kg is pressing in on my whole body, all from all sides. Where does all this pressure come from? It's from the air!
That looks like a dance move! I'm lifting 10,000 kg of air! You're lifting the air! How much air is there above us? About 20 km or so. So you're at the bottom of an ocean of air. So essentially, the weight of the air is squishing me in.
That's right. And all of us— you too and me too. Wow, you seem to be holding up rather well, though! Thank you. Thank you! How do you do it? What is... well, I've got this special trick. Uhh, uhhuh! I've got the same amount of pressure inside me.
Okay, so since the pressure is equal inside and outside of you, you're in equilibrium, and there's no sort of crushing or expansion? No, that's right. Okay, right! Well, most people, I think, don't recognize the pressure that they're under— at least you, the atmosphere.
That's right! How can we demonstrate that the atmosphere is exerting this huge pressure on everyone? The best thing to do is to scoop out their insides, and then there'll be no pressure on the inside, and then they'll be crushed— crushed by the atmosphere!
And that will be a rather clear demonstration exactly of the power of the atmosphere. Exactly! But let's say we didn't want to kill anyone— uh, how can we demonstrate this in, say, a lab? Well, we could take a model of a person, and this drum is meant to be a model of a person!
That's correct, yeah. Okay, and um, so what are we going to do with it? So what we're going to do is we're going to put some water in here. Why don't we go ahead and do it? Okay, let's do it! Get it heating up!
So we've got some water in the drum, and we're heating it up on this little gas stove here. That's right! Okay, and what is that doing for us? So the water will heat up and begin to boil, so it'll turn from liquid into vapor. That vapor will push out some of the air.
Okay, so basically, we're going to remove the air from inside the drum and replace it with water vapor. That's right! Okay, okay! Then once we're sure that it's pretty much emptied of air, we put the stopper in. Mhm. And cool it back down again.
Okay, so that's going to condense the water vapor. That's right! And so what does that do to the pressure inside the drum? It'll become much smaller. Okay, and then we're going to be able to see what the atmosphere does when there's no pressure on the inside.
Push out! Exactly! Alright, well, I look forward to that. Alright, so how long do we have to wait for this to boil and get all sorted? A couple of minutes. Mhm. Should we do a little time-lapse effect? Let's do that!
Alright, okay, looks like we're boiling away furiously here. It's pretty good, so it's about time to perform the experiment! Let's do it! But it might be a bit dramatic, so I'm going to chuck on a bit of gear— safety glasses are always important!
And safety gloves to avoid burning your hands on this very hot drum. That's right! Now, you might want to put those on. I will! You might want to stand back a bit because it's a little bit dramatic what happens.
Alright, let's do it! [Music] Get to there and get some cold water onto it! Alright, so that water's turning back into water vapor! Oh my— [Music] God! [Music]
That's what you look like with 3,000 kg on your head— 10,000 kg on your whole body! You know, I was expecting it to crumple slowly over time. I wasn't expecting it to just go all in once!
Yeah, well, because a little bit goes, and the whole lot goes! Wow, they're quite strong for a while. Yeah, that was awesome! Yeah, you can hear the air is trying to get back in. Ah, and now the pressure is equalized there.
Pressure is now requal! That's right! Wow, that's one hell of an experiment! Certainly is! Looks like you wet yourself! That was so exciting! That's partly— [Laughter] true!