Equation written on a car--Is it a riddle?

[kimberwarden]

I hope this is the right place to post this question. I saw this equation on a car's back windshield. I don't know what it means, but I'm really curious why someone would put it on their car. Is it a riddle of some kind? A famous equation?
http://skonline.org/TruckEquation.gif
Thanks for your help!

[arildno]

It is the (irreversible case of) famous Clausius' theorem in thermodynamics:
http://en.wikipedia.org/wiki/Clausius_theorem

Very important in defining, and understanding, the concept of entropy.

[kimberwarden]

Thank you so much! Since the car the equation was written on was a macho-looking pickup truck, maybe the guy was stating that his truck is hot stuff?

[arildno]

Thank you so much! Since the car the equation was written on was a macho-looking pickup truck, maybe the guy was stating that his truck is hot stuff?
Quite possibly, yes.