Charles said:

"I don't understand how mass is equal to length divided by time."

I agree, it doesn't make any sense. Stranger still, try using those same units for density = mass/volume:

Density = kg/m³

            = m³/(m³*s²)

            = 1/s²

So the density of Gold (for instance) would have units of time (1/s²).

What does that even mean? I can't make any sense of it. How can the density of Gold be expressed in units of time (the inverse of time squared)? Density is mass per volume. How is that in any way related to the passage of time? Even if the units work out correctly, it still lacks a rational explanation.

 --Richard Cage