$2\mathrm{.}4\mathrm{.}14.[$Level $2]$ A particle $P$ is moving along a sinusoidally varying path, its position defined by $y=a[1-cos(x)]$ with $=\frac{1}{320}f{t}^{-1}$ and $a_{P}8\mathrm{.}0i+2\mathrm{.}0j$