一辆值勤的*车停在平直公路上的A点,当*员发现从他旁边以v=9m/s的速度匀速驶过的货车有违章行为时,决定前去...
问题详情:
一辆值勤的*车停在平直公路上的A点,当*员发现从他旁边以v=9m/s的速度匀速驶过的货车有违章行为时,决定前去追赶。*车启动时货车已运动到B点,A、B两点相距x0=48 m,*车从A点由静止开始向右做匀加速运动,到达B点后开始做匀速运动.已知*车从开始运动到追上货车所用的时间t=32 s,求:
(1) *车加速运动过程所用的时间t1和加速度a的大小
(2) *车追上货车之前的最远距离x
【回答】
(1)设*车加速过程所用的时间为t1,加速度大小为a
则x0=at·························································································· (1分)
at1(t-t1)=v t···························································································· (2分)
得t1=8 s·································································································· (1分)
a=1.5m/s2····························································································· (1分)
(2)设经t0*车与货车共速,此时*车追上货车之前最远
t0==6s································································································· (1分)
t0时间内货车运动的距离x1=v t0=54m······················································ (1分)
t0时间内*车运动的距离x2=t0=27 m···················································· (1分)
此时相距x= x0+ x1- x2=75 m······································································ (2分)
知识点:匀变速直线运动的研究单元测试
题型:计算题
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