Needle Through Balloon – Little Shop of Physics
November 9, 2019
MAN: So Sheila, I see you have a knife placed above this balloon. SHEILA: Yes. MAN: If you take the knife and push it into the balloon. Ooh. I think we know what happens. SHEILA: Yes. MAN: And where the knife touches the balloon, what actually happens is the balloon tears, the balloon, actually the fabric is pretty sturdy but once you get a tear in it, the tear will propagate very, very nicely. But now we can do this balloon. If you will hold this one, steady like this. SHEILA: I will. MAN: And I have now, the knife is a kind of a line, it’s a flat structure. So the line is flat. So when I push it in here, it makes basically a linear tear and that tear and that tear just propagates, it spreads. But this pointy bit, it’s very round. And so when this one punches into the balloon, it will make a hole as opposed to a linear tear. And since I don’t have that tear to propagate, it won’t. But the other way to keep the balloon from tearing is, I’m going to take this, and I’m going to lubricate it. So lubricate the tip of the thing a little bit. And I’m also lubricating the table cloth it would seem. So I have a nicely lubricated tip and it’s very, very sharp and it’s very, very round. And if I take this and I put it in the balloon, this particular spot where I’m putting it in is that thick spot on top and I’ll turn it and the key is to take this thing, I’m going to push it in, it’s lubricated. It makes a hole. So the balloon will deflate but the balloon doesn’t actually pop. So choosing the right spot and choosing the right shape, you can actually stick something into a balloon without popping it. SHEILA: So something like a knitting needle would work as well? MAN: A knitting needle would be fantastic. This has … SHEILA: A barbecue skewer? MAN: A barbecue skewer, knitting needle. As long as it’s round, as long as it’s very sharp and as long as it’s slightly lubricated, all systems go. SHEILA: I think I prefer this way of popping a balloon.