Question

1、某段铁路由长度为L的铁轨一根一根地铺成,一列火车在均速前进,车内一位乘客要测量火车运行的速度,他测出了火车经过铁轨接

Answer 1

1.v=s/t=NL/t

2.子弹从枪口到靶的时间:t=s/v=100m/800m/s=0.125s s靶=vt=8m/s×0.125s=10m

3.v1=s/t1=s/1min v2=s/t2=s/3min t=s/(v1+v2)=s/(s/1min+s/3min)=0.75min

4.t=s/v t1=(0.5×s)/8m/s t2=(0.5×s)/6m/s

v=s/(t1+t2)=s/[(0.5×s)/8m/s+(0.5×s)/6m/s]=6.857m/s