前段时间,女儿拿一道物理题让我指导。题目如下:一辆客车在某高速公路上行驶,在经过某直线路段时,司机驾驶客车做匀速直线运动,此时他发现其正要通过正前方的高山悬崖下的隧道,于是鸣笛,经过t1=5s后听到回声;听到回声后又行驶t2=13s,司机第二次鸣笛,又经过t3=3s后听到回声。请你根据以上数据帮助该司机计算一下客车的速度,判断客车是否超速行驶,以 Some time ago, my daughter took a physics question to guide me. The subject is as follows: A passenger car is driving on a highway. When passing through a straight line, the driver drives the passenger car to make a uniform linear motion. At this time, he finds that he is passing through the tunnel under the high mountain cliff in front of him, and then whispers through the road. After t1=5s, the echo was heard; after hearing the echo, t2=13s, the driver whistled for the second time, and heard the echo after t3=3s. Based on the above data, please help the driver to calculate the speed of the bus and determine if the bus is speeding.