Nathan Scandella (personal)

Why Being An Ignoramus Matters

The state of science education in this country is appalling. The feeling that most people have is that their job (or intended career) doesn't directly depend on science, so why should they bother learning about it?

There's a whole bunch of good answers to that question, but today I'll focus on one. Understanding how physics and chemistry (et al) work has practical applications in everyday life.

Right now, Seattle is stuck in the worst prolonged snow storm in the 11 years that I've lived here. There's about a foot of snow on the ground now, and the snow (and cold) are forecast to be here for several more days. This might not sound like much to people back east, or MidWesterners, but here, snow wreaks havoc. People aren't used to dealing with it, we don't have the equipment (i.e. plows) to handle it, and so it's very dangerous. Seattle proper is also a very hilly city.

I happen to live right on one of those hills, at 57th Ave and Admiral Way. 57th happens to be a very steep hill, and is the access point for just about everyone who lives uphill from me. While it's a dangerous hill in the snow, the only other options for getting off the hill are equally dangerous. So, in the spirit of helping both myself, and those who live above me, I decided I would spend some of my spare calories this week actually shoveling the street. This probably seems strange to most, but in Seattle, the city only sends snowplows down the busiest thoroughfares - not sidestreets (hilly or otherwise). So, I decided to do it myself. It was no easy task, and takes about an hour to shovel a reasonable portion of the pavement.

On plenty of occasions, passers-by stopped to thank me. On a few occasions, people have stopped to tell me that I was not only wasting my time, but making the hill more dangerous. Here's why they're wrong:

• In the conditions I was in (snowy, but temperatures around freezing), I actually am able to shovel down to the bare pavement. So, upon completion of my task, pavement was exposed on a large enough section of road to allow traction. I do this every day, so a permanent ice layer has not been allowed to form


• Even though snow may look safe when churned up, underneath a rubber car tire it becomes perfectly flattened. So, while the look of shoveled ground may appear slick - because it's smoother - everything is flat under your tires. The only question is whether your tires are riding on snow, ice, or some pavement


• Some people believe thick snow is safer because you don't have trouble slipping while walking down a snowy slope. First of all, your feet are much different than a car tire. They have nice sharp edges, called heels and toes. Tires are almost perfectly round, and have no sharp edges to dig in (unless you're moving sideways). Tires are spun over the road, not picked up and put down like feet. A foot can dig into its own little snow hole. A tire cannot. If the road itself isn't rough, a tire cannot make it so, as a foot can punching into the snow. So comparing the street to a sidewalk, for example is not valid


• The amount of traction you have on the ground depends on something called the coefficient of friction between two materials, such as your tire, and the ground. Not only is the coefficient of friction higher between rubber and pavement, compared with rubber and snow or ice, but there is another effect. For any two materials, there are generally two coefficients of friction. A static and kinetic (dynamic) one. In this case, the coefficient of static friction between tires and the ground is much higher than the kinetic one. In dry conditions, tires should not be sliding at all, so the applicable coefficient of friction is the static one. The portion of your tire that's contacting the road is actually moving at zero mph over the ground, for the instant it touches the ground. However, once a bit of snow enters the equation, tires will be slipping against the ground, and thus the (lower) coefficient of kinetic friction applies. This means spinning car tires are even more vulnerable to slippery conditions. The only solution is to give the tires something rougher to run over. Pavement's surface actually is rough. A thick layer of slushy snow will not allow the tire to touch pavement, and will thus have the tire floating on a slippery layer of fluid material


• If the snow keeps falling, of course, some of the benefit of my shoveling is lost. But, the result is only as bad as an unshoveled street, in the worst case. More than likely, the snow layer will be thin enough (after shoveling), that heavy cars will be able to push down through the snow and hit some pavement


• If shoveling really made a street slicker in such conditions, I can assure you that cities would not run snowplows until the snow got so deep that cars didn't even have enough ground clearance to get through it. But, snowplows are used on streets with only a few inches of snow, because it works.


• By removing some of the snow layer each day, the process of ultimately melting the snow, and returning to dry pavement is accelerated. All the snow doesn't go away the instant the temperature reaches 33 degrees. The less snow there is left on the road, the sooner it will be completely gone.


• There's a related point, based on the fact that pavement is black and snow is white. During the day, when the sun comes out, a dark road will warm up more than a white road. So, by exposing even a little pavement, you are allowing the sun (no matter how little of it there is) to help you remove even more snow.


• If you do no snow removal, and let cars drive on the slush, their weight will compact the bottom layer into something that will freeze overnight (assuming temperatures are well below freezing, as they have been here). The next day, that slush will be covering a layer of ice, that even shoveling will have a hard time removing. By removing all but the newest snow each day, you prevent the most treacherous thick ice layers from forming at night, which are much more difficult to remove. And while slush is slippery, solid ice is the worst.

Ok, enough with the theory. How about in practice? Well, as you have it, my window just happens to be looking at this dangerous hill from a perfect side view. So, several times a day, I get to see cars and trucks going up and down my hill, with a view close enough that I can tell if their wheels are slipping or not. Obviously, I can tell if they can successfully come to a stop at the bottom of the hill.

The results were dramatic. With shoveling, almost all the cars have been able to make it up my hill, and stop with limited amounts of hydroplaning on the way down. Before I shoveled (in the morning), I only saw one vehicle, out of about a dozen, successfully make it up my hill. This was a large pickup truck, with double-wide rear tires, and a large head of steam entering the turn. Of course, I have also gone up and down the hill in my car, a Subaru Outback wagon with AWD, but no chains. The difference in traction on the shoveled, and unshoveled parts of the road is dramatic. I also noticed a small Land Rover, driving up some of the unshoveled section, only to come to a spinning stall halfway up the hill. He slowly slid back down the hill. On his second attempt, he went up the section I shoveled (the other side of the road) and made it easily. He then proceeded further up the hill, to a less steep section that I didn't shovel. On that section, he fishtailed a little even though the hill wasn't even as steep as the section he just made it up!

I certainly couldn't call myself a good scientist if I relied merely on theory. I observed the results, and even was willing to put my safety on the line to test out my theory (also to get my car down the hill!). All signs pointed to my efforts being of benefit, going up and down the hill. It will probably snow more tonight, so I'll have to do it again tomorrow. But, I'll then have less shoveling to do than if I hadn't stayed on top of the snow all along.

So, in this case, understanding a little bit about classical mechanics (that's a part of physics) helped me make my local street a little more usable. Despite urging from a couple of ignorant neighbors to stop. One of them even stopped in the middle of the hill, to lecture me. I didn't point out that stopping to yell at me was enabled by my shoveling. As he drove off down the hill, I said to him (window down), "I see you stopping [at the bottom of the slope], don't I?". He replied, "yeah, that's because I've got it real low, with the 4x4 on".

Gearing down on slippery slopes? Wow, that is brilliant. Who else but such a genius would ever have thought to try that? I wish I was quick enough to yell back that having 4 wheel drive doesn't help you going down a steep slope. In that case, you're certainly not giving the car any gas, so the drive wheels aren't doing a thing. Now, if his truck had Antilock Brake Systems, that would help out. But, the fact that he thought having a 4x4 was the reason he so easily made it down my hill was somewhat amusing.

Unfortunately, I can't shovel all the streets. And there are lots of people out there making decisions about all kinds of things, who don't ask for my opinion. I just wanted to stress how understanding things like physics and chemistry and biology helps in all sorts of different ways. It may be annoying to have the geeks be right so much of the time, but society would be better served if they better appreciated an understanding of science, instead of reveling in their unscientific web of old wives' tales.

Posted at 11:17PM Dec 21, 2008 by Nathan in Environment  |  Comments[0]