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I recently posted a complaint about physics misconceptions promulgated by the media. To be fair, I need to report a good job describing the physics of a situation when it appears.
In an article posted on Dec. 27, 2006 by the op/ed staff of the North County Times (near San Diego), and titled A Physics Lesson, the authors do a very nice job of describing the role of friction in driving:
Your tires rely on friction to speed up, turn or stop. On a dry day, there's usually plenty of friction when the rubber hits the road. When it rains, the weight of your car must push water out of the way for the tires to reach the road.
The faster you drive, the greater amount of water your tires must push aside. If that water gets trapped between the asphalt and the tires, you'll lose control of your car -- you'll be hydroplaning. The lesson here is that when the roads are wet, you can't drive as fast as you would on a normal day. Even if the rain is light, slow down at least five to 10 mph.
When I teach a first-semester course in Physics, I typically begin the first day trying to get students to identify forces acting on them as they do basic things. My favorite example is on walking. I ask the following question: if you go from standing still to walking at a steady pace, you accelerated. According to Newton there must be an unbalanced force acting on you in the direction of your acceleration. What is this force?
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