# Answer

Not at all: `position` is a function that takes one argument, and `vel`
is an expression. If we want to calculate the position of the destroyer at
time 10, we can simply ask Maple to evaluate `position(10)`. But if we
want to calculate the velocity of the destroyer at time 10, we'll have to type
the `vel` expression back in, substituting 10 for `t`. This isn't too
bad in the present case since the expression is so simple, but it would be a
major pain with a complicated formula.
Return to lesson.

*Joseph L. Zachary *

Hamlet Project

Department of Computer Science

University of Utah