石块A自塔顶*落下x1时,石块B自离塔顶x2处*落下,两石块同时落地,则塔高( )A.x1+x2B.(x1+x2)^2/(4x1)C.x2/[4(x1+x2)]D.(x1+x2)^2/(x1-x2)要讲理由
问题描述:
石块A自塔顶*落下x1时,石块B自离塔顶x2处*落下,两石块同时落地,则塔高( )
A.x1+x2
B.(x1+x2)^2/(4x1)
C.x2/[4(x1+x2)]
D.(x1+x2)^2/(x1-x2)
要讲理由
答
选B
x1=1/2 g t1^2
h-x2=1/2 g t2^2
h=1/2 g (t1+t2)^2
===>h=(x1+x2)^2/(4x1)