The postion versus time graph of a body undergoing constant acceleration is a ...

Under constant acceleration the position versus time equation is:

X = Xo + Vo*t + a * (t^2) / 2

Where:

Xo is the initial position

Vo is the initial velocity

t = time

a = acceleration

That equation is a second grade polynomial which is a parabola.

So the word that completes the statement is "parabola".

Answer: parabola