\(\Rightarrow\left\{{}\begin{matrix}t1=t\left(AB\right)=2,5h\\t2=t\left(BC\right)=\dfrac{100}{60}=\dfrac{5}{3}h\end{matrix}\right.\)\(\Rightarrow t1>t2\left(2,5h>\dfrac{5}{3}h\right)\)
\(\Rightarrow nước\) \(chảy\) \(từ\) \(B->A\)
\(\Rightarrow\left\{{}\begin{matrix}\left(vt-vn\right).t1=AB\\\left(vt+vn\right)t2=AB\end{matrix}\right.\)\(\Rightarrow\left(vt-vn\right)t1=\left(vt+vn\right)t2\Leftrightarrow\left(20-vn\right).2,5=\left(20+vn\right).\dfrac{5}{3}\Rightarrow vn=4km/h\Rightarrow AB=\left(20+4\right).\dfrac{5}{3}=40km\)
Đúng 0
Bình luận (0)
