More Math Help

My wife's job involves developing math textbooks. We're rock solid on math & how kids learn it & how to teach/explain/troubleshoot it from preschool up to Grade 9 or so. Today's task, however, has us scrambling a bit. For a Canadian Grade 11 textbook, what sorts of real-world situations would you use to illustrate times when a quadratic equation might have two, one, or no solutions?

(I'll even take something where the answer is "Miata" if it comes with a convincing explanation of why.)

Thanks in advance!

Quadratics... Hm... Well, basically applied mathematics=physics or finance.

So I'd go for trajectory stuff, like at what angle/speed/whatever should the submarine fire its torpedo...braking distances... Sorry, I'm kinda in a study coma and can't give you specific examples.

Constipated mathemeticians work it out with a pencil.

Cross sections of roofs is a good visualization.

Thanks for these, everybody. Any more ideas out there?

Real world situation: When you're trying to find the solution to a calculus problem that stand between you and failure on a midterm.

Seriously, there isn't all that much straight real-world usage of the quadratic that is just the quadratic. You'll use it a lot in calculus and linear algebra--those have plenty of real world applications--but the equation in itself isn't used a whole heck of a lot.