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我梦见我踩单车送一个老人回家,他家门右边有个小...

(1)∵v=st,t1=20min=1200s,∴路程s=v1t1=1.2m/s×1200s=1440m;(2)骑自行车的速度:v2=st2=1440m60s×8=3m/s;答:(1)从家门到校门的路程大约是1440m;(2)骑自行车的平均速度是3m/s.

(1)∵v 步 =1.2m/s,t 步 =15min=900s,∴由 v= s t 得S=v 步 t 步 =1.2m/s×900s=1080m.(2)∵S=1080m,t 骑 =6min=360s;∴v 骑 = S t 骑 = 1080m 360s =3m/s.答:从家门到校门的路程大约是1080m;该同学骑车的平均速度是3m/s.

(1)∵v步=1.2m/s,t步=15min=900s,∴由 v=st得S=v步t步=1.2m/s×900s=1080m.(2)∵S=1080m,t骑=6min=360s;∴v骑=St骑=1080m360s=3m/s.答:从家门到校门的路程大约是1080m;该同学骑车的平均速度是3m/s.

由题意,学生运动的时间为15分钟,即t=900s,一般高中学生的质量约为50kg,自行车车的质量为20kg,摩擦力约为重力的0.15倍,速度约为v=4m/s,则两者合计重力为G=70×10N=700N,则阻力为:f=0.15G=0.15×700=105N,从家到学校的位移为:x=vt=4×15×6...

(1)∵v=st,t1=15min=900s,∴从家门到校门的路程:s=v1t1=1.2m/s×900s=1080m;(2)骑自行车的速度:v2=st2=1080m480s=2.25m/s;答:(1)从家门到校门的路程大约是1080m;(2)骑自行车的平均速度是2.25m/s.

(1)t=10min=600s小明从家门到校门的路程大约是,由v=st得:S=vt=1.2m/s×600s=720m (2)t′=4min=240s骑自行车的平均速度是v′=st′=720m240s═3m/s 答:(1)小明从家门到校门的路程大约是720m(2)小明骑自行车的平均速度是3m/s.

(1) 1080m (2)3m/s 试题分析:根据步行速度与所需时间求(1)t 1 =15min=900s t 2 =6min=360s S=v 1 t 1 ="1.2m/s×900s" =1080m (2)v 2 =" S/" t 2 =1080m/360s=3m/s

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