[填空题]
A squirrel is climbincu,w: osidw 0zvd;h 3 g,5ix5wg a trefxl- c/t ,/vqte5u 6zve 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