Question

Giúp ạ

Answer 1

6C

Bài 8:

a. Đổi: \(\left\{{}\begin{matrix}112\left(\dfrac{km}{h}\right)=\dfrac{280}{9}\left(\dfrac{m}{s}\right)\\88\left(\dfrac{km}{h}\right)=\dfrac{220}{9}\left(\dfrac{m}{s}\right)\\77\left(\dfrac{km}{h}\right)=\dfrac{385}{18}\left(\dfrac{m}{s}\right)\\71\left(\dfrac{km}{h}\right)=\dfrac{355}{18}\left(\dfrac{m}{s}\right)\end{matrix}\right.\)

b. Thời gian để báo (1) và ngựa (2) chạy hết:

\(\left\{{}\begin{matrix}t_1=\dfrac{s_1}{v_1}=\dfrac{100}{\dfrac{280}{9}}=\dfrac{45}{14}s\\t_2=\dfrac{s_2}{v_2}=\dfrac{100}{\dfrac{355}{18}}=\dfrac{360}{71}s\end{matrix}\right.\)