# What Is the Power to Run Through Football Players — from “How To”

I’m continuing to work on explanations for the Randal Munroe book How To — Absurd Scientific Advice for Common Real-World Problems (Penguin Press). Basically, it’s a book that just has a ton of fun answering weird questions with some cool cartoons.

There is a chapter about scoring in an NFL football game. One idea is to just use a horse and literally plow through the opposing team. It’s just like a scene from Lord of the Rings with a horse running through a sea of orcs. Honestly, I can’t remember exactly which movie this was.

So, here’s the stuff from How To. First he uses the orcs as though they were a drag force with the following equation (for the magnitude of the drag force).

In this expression:

• ρ is the density of the medium. If you were moving through air, it would be the density of air. In this case, it’s the crowd density of orcs.
• A is the cross sectional area of the object. For a horse, this would be the front surface area.
• C is a drag coefficient that depends on the aerodynamic shape of the thing.
• v is the relative velocity of the object with respect to the medium.
• Oh, the 1/2 is the number 0.5. Ha.

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Physics faculty, science blogger of all things geek. Technical Consultant for CBS MacGyver and MythBusters. WIRED blogger.