Question

[Ẩn danh]

giúp tôi với! Tôi cần gấp lắm! Cảm ơn nhiều!

Answer 1

[nthv_.]

\(15\left(\dfrac{m.}{s}\right)=54\left(\dfrac{km}{h}\right)\)

\(\Rightarrow v_{tb}=\dfrac{s}{\dfrac{\dfrac{1}{2}s}{v'}+\dfrac{\dfrac{1}{2}s}{v''}}=\dfrac{s}{\dfrac{s}{36}+\dfrac{s}{108}}=\dfrac{s}{\dfrac{4s}{108}}=\dfrac{108}{4}=27\left(\dfrac{km}{h}\right)\)

\(TBCv_1-v_2=\left(18+54\right):2=36\left(\dfrac{km}{h}\right)\)

\(\Rightarrow v_{tb}< TBCv_1-v_2\left(27< 36\right)\)

Vậy ta đc đpcm.