A particle is moving along a straight line such that its acceleration is defined as $a=(-2 v) \mathrm{m} / \mathrm{s}^{2},$ where $v$ is in meters per second. If $v=20 \mathrm{m} / \mathrm{s}$ when $s=0$ and $t=0$ determine the particle's position, velocity, and acceleration as functions of time.