[填空题]
1. Define distance.
gm2*g fhyn*u4b*b;excz+cs a *)m) jh 2.An object moves in a straight line on a level road. The variation of the object's distance $d$ with time $t$ is shown on the graph below.
(1)Describe the motion of the object between $t=0.5\,s$ and $t=1.0\,s$.
(2)Calculate the instantaneous speed of the object at $t=0.5\,s$. $v$ = $ms^{-1}$
(3)On the axes below, sketch a possible graph of the variation of velocity $v$ of the object with time $t$. There is no need to add values to the axes.
4.Determine the direction of the change in momentum of the object during the motion is the direction of motion.
