|Note that the initial velocity is negative (slope of the curve at t=0.) The
graph can be devided in two portions, the part before the position reaching a minimum
(maximum displacement from the origin but in the negative direction.) and the portion
after the minimum. You can deduce from the first portion that the acceleration is positive
since the speed is decreasing (the slope is leveling off.)
Note the motion of the puck. It starts moving in the negative direction and reverses
direction when the curve reaches the minimum.