题目

 You’re sitting in the car, stuck(无法离开的) in traffic. You’re going to be late for school! If only the car could lift(升起) up and fly all the way to the school gate. Well, now you can realize(实现) your wish .      Engineers from the UK built a flying car, called the SkyRunner. This special vehicle(车辆) can reach 185km per hour on the road as a normal(正常的) car, and then fly in the sky at 90km per hour. As the car takes off the ground, a parachute (降落伞) at the back shoots(发射) up and begins lifting the car. Now you’re ready to fly! It lets you fl如图所示，放在水平地面上质量均为1kg的两个小物体A、B相距8m，它们与水平地面的动摩擦因数均为μ=0.2，现使它们分别以初速度vA=6m/s和vB=2m/s同时相向运动，直到它们相遇时，两物体克服摩擦力的总功是______J，经历的时间是______s．（重力加速度g取10m/s2）．