The Physics of Speed (and the value of multiple Ortizes)

Thanks to this book, Neil and I watched the 1994 movie Speed for his physics lesson today. As a physics lesson, the movie is absurdly amusing. If you don’t know the movie, the general premise is that a madman, unhappy with his pension plan, has placed a bomb on a public transit bus, and once the bus goes faster than 50 miles an hour, it can never go slower than that, or it will explode. Only the fast thinking action hero bomb squad skillz of LAPD officer Jack Traven (played by Keanu Reeves) and the gutsy trick driving talent of Annie Porter (Sandra Bullock) save the day. That and super physics, but more on that later.

As Keanu Reeves answers a public pay phone in the vicinity of a recently exploded bus in order to have the bomber taunt him, I had to point out to Neil that there was once a day when not everyone had a cell phone. Nonetheless, this was modern enough that both the bomber and the rich dude from whom Traven takes one (after having carjacked and damaged his car) had the big bulky kind which looked like walkie-talkies, allowing them to communicate the way we do today.

After speeding along an off ramp and then in crosstown traffic, the bus needs to take a 90 degree right turn. Any physicist will tell you that big public transit buses cannot make 90 degree turns, and even then, they need to take their turns slowly or else the bus will topple. In the movie, the bus makes the turn and manages not to topple as all the passengers move to the left side of the bus.

Neil assured me the weight of the bus had nothing to do with calculations on whether this is possible: it all has to do with the velocity of the bus, the width of the bus, and the friction between the bus and the tires. We can give some leeway to the fact that Annie the driver may take a wider-than-road turn even if if involves driving on the embankment and smashing into things (as she has been doing). But the balance and friction would be better with bigger, denser passengers. There is one character named simply, Ortiz, whom Travers initially called “Gigantaur” and as physics calculations revealed, more of him would have made the movie more plausible. If all the passengers had been Ortizes, their very mass would have kept the bus’s center of mass lower and thus made the bus less likely to topple in a fast turn.

Later in the movie, Annie gets the bus up to a roaring 70 miles an hour to jump a 50 foot gap between freeway portions. Sadly, given that any ramping is minimal, and because of air resistance, physics says the bus could never make it–once again, the actual weight of the bus isn’t a factor, though speed (velocity) and angle are. However, as Neil and I (as well as the book author) noticed, the bus inexplicably makes a wheelie as it takes off, even though we knew all the passengers were crouched in their seats for a crash landing. Once again, we see the value of multiple Ortizes. If the bus had been filled with Ortizes, they could have all hurled themselves against the back door of the bus, thus causing the wheelie and allowing the bus to have a sufficient angle to make it to the other side of the gap.

Physics thus gives us two important lessons. If you get on a bus in the Los Angeles area and you find it nearly full with gargantuan Hispanic men, and a twitchy person playing a racing game on his or her cell phone, you will probably be safe when a Speed-type emergency arises, unless one of them succeeds in shooting the LAPD officer when he gets on the bus after having carjacked a car. Or you can do what most Angelenos do, and drive a car, regardless of whether you have a license to do so.

As a fiscal conservative, I found myself offended by another part of the movie. If I heard correctly, the bomber, Howard Payne, only wants $3.7 million. At one point he snarls to Traven “Grow a brain, Jack,” but, no, Howard, it is you who should grow a brain! He’s spent hundreds or thousands of hours planning his terrorist exploits, thousands of dollars getting explosives and equipment, and more renting an unfinished office downtown and setting it up with expensive equipment, as well as putting then-state-of-the-art video transmitters into LA buses. Oh, and he rigs up his own million-dollar house to explode when the SWAT team comes to find him. All that for $3.7 million? I’m pretty sure you can retire and collect very nearly that much by retiring early as a California public school teacher or firefighter, and you could do far better than that by hiring yourself out as a consultant to a federal agency for a few years. Just shill yourself as the best candidate as Explosives Czar, dude, don’t blow up your house and destroy your neighborhood’s real estate values!

It also would have been cheaper to pay him off, because that bus (and later, the subway train) did a heckuva lot more than $3.7 million worth of damage. There were a whole lot of smashed cars, and in the end, the bus ran into a billion dollar airplane and blew it up. And don’t even ask me about the cleanup for a subway car that breaks up and smashes through a subway station wall and into downtown LA traffic. There isn’t a federal slush fund big enough to cover that, and don’t even think about asking the California governor for emergency money on that. He really really really doesn’t want to hear it now. Just give the terrorist douchebag his money. Yeah, yadda, yadda, moral hazard, and the terrorist will probably blow everyone up anyway, but if he doesn’t, it’s a lot cheaper than the alternative, which is this case included the gratuitous murder of 6 LAPD officers. After all, they already had his identity (which he wanted them to have), and they put a tracking device on the money, which he hadn’t bothered to check for. Again, who’s the person who needs to grow a brain in this movie?

Well, it was a fun anyway. And I did find out from Mythbusters that it is possible to skip a lightweight sportscar over a small body of water, something I will keep in mind if I’m ever trying to outrun the cops in a small sportscar in an area with many small lakes. Even if I’m caught, I’m sure a good defense attorney can say I was just trying a physics experiment…not actually running from the law.