$($f$)$ An object starts from rest and accelerates uniformly. If it moves $2$ meters during the first second, then during the first three seconds, it will move $6$ meters $9$ meters. $10$ meters. $18$ meters. $($g$)$ A frog leaps vertically into the air, encountering no appreciable air resistance. Which statement about the frog's motion is correct? On the way up$,$ its acceleration is$9\mathrm{.}80$m$/$s$2$upward, on the way down its acceleration is