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

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".

parabola

Letter a, because when there are unlike charges they will always attract to each other.