A particle moves along the x axis. Its position varies with time according to the expression x=-4t +2t^2, where x is in meters and t is in seconds.3 The
position–time graph for this motion is shown in Figure 2.4a. Because the
position of the particle is given by a mathematical function, the motion of
the particle is completely known, unlike that of the car in Active Figure 2.1.
Notice that the particle moves in the negative x direction for the first second
of motion, is momentarily at rest at the moment t=1 s, and moves in the
positive x direction at times t=1 s.

(C) Find the instantaneous velocity of the particle at t 5 2.5 s.