[填空题]
A particle P startsr 2 2e9h2t6efms +obks from avsrw/ xd5zlkc)/g) p4 fixed point O and moves along a horizontal straight line. Its velocw4lg v )rskcz/ p5/dx)ity v $\mathrm{~ms}^{-1}$ after t seconds is given by
The following diagram shows the graph of v .
1. Find the initial velocity of P .
v(0)= ms$^{-1}$
2. Find the acceleration of P during the first second.
a= ms$^{-2}$.
3. Write down the number of times the particle changes direction in the first 8 seconds. Justify your answer.
4. Find the total distance travelled by the particle in the first 8 seconds.
d= m .
