# Why is H always* the letter used to describe the level of a barrier?

A quick and (hopefully) easy question. Why?

*(always / often / when it's not B)

• Is that for real? – Kiwiakos May 23 '16 at 11:36
• @Kiwiakos as in is it a real question? Yes! i'm curious. – will May 23 '16 at 12:24

## 1 Answer

I do not have any reference, but I think $H$ is for hitting.

• Just did a little more digging - it looks like it's more likely related to the Heaviside function. – will May 23 '16 at 12:41
• It's the "height of barrier" so H and B are natural choices for the variable. It is also the "level to be hit" so again H is natural. – noob2 May 25 '16 at 15:32