Car windshields and Styrofoam cups

Diandra Leslie-Pelecky, guest blogger at Cocktail Party physics, has an interesting post, complete with equations and back-of-the-envelope estimates, on whether a Styrofoam cup can break a windshield. Her instinctive answer is: of course not. It's a Styrofoam cup! Then she saw the pictures - she was asked the question by a local reporter after someone in a car discarded a cup of soda through his or her window, cup that then smashed the windshield of a poor woman who happened to drive by in the opposite direction.

For those of you who can't get over the fact that all this damage was caused by a Styrofoam cup, the key isn't the cup (very light), but the soda that was in it (much heavier). As Leslie-Pelecky writes, "We know it was a cup of soda because, in addition to poor Marilyn [the innocent driver] getting wet, there is sticky dried cola-colored liquid all over the inside of the car.  The police pulled part of the cup out of the windshield (which is how we know it came from Sonic) and found a shredded straw inside the car." (The driver was lucky to be wearing glasses,which "were pitted from where pieces of windshield glass hit them.")

Leslie-Pelecky proceeds to estimate the force with which the cup full of soda hit the windshield, coming up with a range of 24-120 pounds because of the lack of data on the angle at which the cup hit the car and other parameters. It's a fun article to read for people who like science; Leslie-Pelecky points out that more kids might become interested in physics if high school exercises were more relevant to real life. But when it comes to throwing your cup of soda out of your moving car, the moral of the story is that it's a big no.

Comments

[Rod Carvalho]

I don't know what high-school Physics in the U.S. is like, but where I come from the high-school exercises were rather relevant to real life imo. I remember exercises with cannonballs, elevators, bridges, cars, rockets, bicycles. It was the most fun I had in high-school :)

[Aurelie]

My physics courses in high school were very boring and serious affairs. There was no connection to real life - it was always about some unidentified object on some unidentified surface. I only started liking physics after I bought popular science books, years later.

[Rod Carvalho]

I think it would be possible to make high-school Physics more interesting and connected to the real world by introducing numerical methods early on. I think the way Physics is taught is almost obsolete. The world has evolved, but the teaching methodology has remained virtually the same for the last two centuries.

It's important to solve problems analytically, but in the real world there seldom are closed-form solutions. Instead of cylinders rolling down an inclined plane (which is somewhat boring), one could use MATLAB to integrate Newton's equations and simulate the flight of the Space Shuttle, for instance. Using numerical integration one could solve problems which are simply too difficult to solve using pen and paper alone.

Would understanding be compromised? I don't think so. High-school Mechanics is mostly solving Newton's equation. It's just one ODE. There's nothing particular deep about that. Teaching the differential formulation of physical problems early on and solve them with finite difference methods would be a whole lot more instructive in my opinion.

Sad to hear that the teaching of Mechanics in France has also become dull. Lagrange, D'Alembert and Maupertuis must be rolling in their graves. OK, Lagrange was actually Italian, but he worked in France a long time...

[Aurelie]

That's a great idea! Students using the computer to solve complex physics problems would feel more like scientists. It's hard for high school kids to feel motivated if they think they're reinventing the wheel, which is what happens when they have to do exercises with pen and paper, or even a simple calculator. In school, I rarely felt like what I was learning was connected to the real world (never in high school, never in the two years of study leading to the entrance exams of the French engineering schools, a little more often during my time at the Ecole des Mines - and then only when the course was taught by a researcher from the school's research labs, because he would make the course content more practical and would show us what it meant to do work in his field.)

Things are changing, though. In the nonlinear optimization course I taught about two years ago, I noticed some students were experts in Maple and Mathematica. I had assigned an exercise about computing the gradient and Hessian of specific functions in the homework, and they handed in the Maple printouts. I'll admit I hadn't even thought about them not doing it by hand! (I'm a Matlab user.) While it's always good to know how to answer a question without the computer to help you out, the future of science isn't about calculating first and second partial derivatives on a piece of paper, when computers can free you to do much more interesting work.