This conversation clearly isn't going anywhere, so I'll leave you with one last thought: no matter how much physics you know, there's always somebody else who knows more than you. If you were going to cite physics to make comments like a jerk, people will call you out on it.

So you'd gladly waste your time on Gizmodo conversing with strangers but now your time is too valuable? Sure.

If it's not that difficult, then why don't you show me how it's done?

Seeing you try and explain complex real-world phenomena with a Physics A1 equation is making me cry.

You keep saying helmets don't stop concussions. The value of helmets is that they reduce the risk of getting a concussion. They stop some concussions, not all.