Question

一物体从斜面顶端由静止开始滑下,最初2秒内的位移是最后2秒内的位移的4倍,且最后一秒内的位移为18m,求

Answer 1

设下滑时间为t,则

1/2at^2-1/2a(t-1)^2=18

S1=1/2aT^2

S2=1/2at^2-1/2a(t-2)^2

题应该是S1/S2=1/4

t=10s

代入(1)式得a=36/19m/s^2

s=1/2at^2=94.74m