Pennies and Formula One cars: Expert separates fact from fiction in these two myths

Ahmed Samir Ead, an assistant professor at the University of Alberta, joined CTV Edmonton Morning Live to separate science fact from fiction with two well-known myths.

 

This transcript has been edited for length and clarity.

 

Kent Morrison: Would a penny falling off the Empire State Building actually do damage? It's something we've thought about since we were kids, and we think we know the answers, but maybe we don't. This is something that seemingly has been in everybody's mind since they were a kid, “Hey, don't drop pennies off a tall building, because it could kill somebody.” Is that true?

Ahmed Samir Ead: Short answer is no, not true. If you're walking in Toronto and you see a penny dropping towards you, don't freak out. It's not going to kill you.

Kent: It would probably hurt, though.

Ahmed: It would hurt a little bit, but not as much as people think.

Kent: It's not going as fast as we think it would be?

Ahmed: No, and I think people's perception of it comes from a myth. It happened a few years ago that someone dropped a penny from a building and it actually got embedded into the concrete. I think people assume that because it got embedded into concrete, that means that it would embed itself in your skull, or penetrate your skull, or something of the sorts. But that’s not true.

Kent: Interesting. Glad to know that. Now, let's talk about something a little bit further afield, a Formula One race car. With the air foils, could it actually go upside down in a tunnel?

Ahmed: That's a cool question. Let me ask you, you have a Formula One car, and it's driving, and decides to enter a tunnel, then it decides to move, traverse the wall and travel upside down. Do you think a Formula One car can travel upside down?

Kent: No, I don't think it could. But I'm thinking about my son's Hot Wheels, and when they go through the loops, if you're going fast enough, they can sustain it. So maybe it depends on how long the tunnel is?

Ahmed: You're close. I think this one is cool, because we see this a lot in the media, right? We see it in movies, we see cars travelling upside down in tunnels. But when it comes to a Formula One car, they are actually designed in such a way to produce a force called downforce. You can think about it like a plane uses lift in order to take off, if you think about the wings, how air travels over the wings, produces lift, pushing that plane upwards. In a Formula One car, we take those exact same kinds of wings, we put them at the front, and we reverse them. So instead of them producing lift, we cause them to produce downforce. This allows the car to travel a little bit faster and to make tighter turns. Now, because there's a force pushing it into the ground, if this car is upside down and you have that force pushing it into the ceiling, you could actually get the car to travel upside down.

Kent: Let's talk about some of these myths, like the penny one. Why do you think it spreads so far, if it's just not mathematically true?

Ahmed: I think it's the allure of the unknown. We're much more willing to believe that something will hurt us, than something that won't. If you think about it, typically we try to avoid situations that may cause death, and we are very intrigued by this whole element of allure and dazzle. The penny myth, I think it's something so common, and we deal with coins all the time, so if it's something so common, how can something so common be so deadly? That's how it propagates. When you look at the math, it's actually pretty straightforward, right? If a penny is travelling downwards, there's a drag force that's causing a resistance to its movement, and it eventually reaches terminal velocity - the point at which all the forces on it balance out, and it travels at a constant velocity. If you calculate that constant velocity, and you calculate the impregnated force on a person, you'll realize that the force is actually not that high. If you drop a penny, it typically won't fall that way (Upright), it will typically fall in a number of orientations, it'll keep on moving in different directions. So when we're looking at the myth, in my class for instance (MEC E 415), what we do is we try to decide what orientations it will fall in. There's a lot of research done that looks and shows that a penny will fall in both orientations almost equally. We then have to try and understand how drag works on each side, and take assumptions based on that.

Kent: Either way, it's not going to hurt you. Wow, that's fascinating stuff. Ahmed teaches a class on this kind of thing at the U of A (University of Alberta) and has the number one YouTube channel right now in Egypt, so go check him out.