问题详情:
在刚刚结束的校运动会上,一年九班获男子4×100m接力第一名。设该队*乙两同学在直跑道上进行交接棒,他们在奔跑时有相同的最大速度,最大速度为vm=8m/s,乙从静止开始全力奔跑需跑出s0=16m才能达到最大速度,这一过程可看做是匀加速直线运动,现在*持棒以最大速度向乙奔来,乙在接力区伺机全力奔出.
(1)求乙加速过程的加速度a的大小
(2)若要求乙接棒时奔跑的速度达到v=6m/s,求乙在接力区须奔出的距离s
(3)如果乙是傻傻站着接棒,接到棒后才从静止开始全力奔跑,求这样会比乙恰好达到最大速度时接棒浪费的时间Δt
【回答】
(1)乙从静止加速到最大速度vm2=2as0························································· (2分)
得a= 2m/s2·························································································· (1分)
(2)乙从静止加速到6m/s
v2=2as·································································································· (2分)
得s=9 m······························································································· (1分)
(3若乙以最大速度跑出16m的时间为
t1=2 s·································································································· (2分)
若乙以匀加速跑出16m
x=at22得t2=4s················································································· (2分)
Δt= t2- t1=2 s······················································································· (2分)
知识点:匀变速直线运动的研究单元测试
题型:计算题