[填空题]
A squirrel is climbiecr8,rwmur5 v1,4d3h5w 1ar nqu0b wc a3ip o:)c-xb6 o z)u0u jaruhv*r2y)ing a tree with velocity $v \mathrm{~ms}^{-1}$ for 9 seconds. This is shown in the graph below.
1. Write down the squirrel's velocity at t=4 .
V(4)= m/s
2. Find the squirrel's acceleration at t=2 .
m= m/s
3. Find the total distance travelled by the squirrel.
d= m
