Lisa, come look at something I wrote and posted at a physics forum

[Lisa]

We'll show them the cross graph

[peter quinn i.e. manoman]

Y=mx+b. This is where the it crosses the axes point.

[peter quinn i.e. manoman]

If you drink a bottle of beer, that crosses the axes point.

[peter quinn i.e. manoman]

If my left ball blew up, it wouldnt cross the plank, but would cross the axes.