January 11, 2010

• Cueball
• Ponytail

#687: Dimensional Analysis explain

My Hobby:

Abusing dimensional analysis

[On a blackboard.]

(Planck energy/Pressure at the Earth’s core) x (Prius combined EPA gas mileage/Minimum width of the English Channel) = π

[Cueball indicates this equation with a pointer in front of a class.]

Cueball: It’s correct to within experimental error, and the units check out. It must be a fundamental law.

Student: But what if they build a better Prius?

Cueball: Then England will drift out to sea.