Back many years ago, a friend in graduate school asked to come along as an adviser when he went car shopping. I mentioned that I did not know much about cars, but he thought I might be useful anyway until I mentioned that it was not until shortly before this that I had learned that a car cannot have both a carburetor and fuel injection.
Coming back from Arizona the other day, one of my tires hit a nail. The tow truck driver attempted to fix the tire, indicating that I would not need to take the tire in for repair. Unfortunately, the fix did not last, and it turned out that the tire would have to be replaced. While I waited to have the tire fixed, I was watching another car being serviced. This is the first time I remember actually seeing a brake pad. I had envisioned something much bigger and clumsier. In fact, even though this was actually a pickup truck, it was a much smaller and handier item than I had ever imagined.