已知平面直角坐标系xoy上的区域D由不等式组$\left\{\begin{array}{c}\begin{array}{c}0\le x\le \sqrt{2}\\ y\le 2\\ x\le \sqrt{2}y\end{array}\\ \end{array}\right.$给定．若M（x，y）为D上动点，点A的坐标为（$\sqrt{2}$，1）．则$z=\overrightarrow{OM}·\overrightarrow{OA}$的最大值为（    ）

为了安全，我国公安部门规定，高速公路上行驶的汽车之间应保持必要的距离．已知某高速公路上汽车行驶的最高速度为120km/h．遇到突发事件驾驶员的反应时间（从发现情况到采取相应行动所经历的时间叫做反应时间）为0.6s，轮胎与路面之间的动摩擦因数为0.32．计算时g=l0m/s²．

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