Question

Two water pipes of diameters $4cm$ and $8cm$ are connected with main supply line. The velocity of flow of water in the pipe of $8cm$ diameter is ----times that of $4cm$ diameter pipe.

• A. $4$
• B. $\frac{1}{4}$
• C. $2$
• D. $\frac{1}{2}$

Answer 1

The correct option is B $\frac{1}{4}$

The volume rate of flow of water is same throughout the pipes.

Hence $Q=A_1{v}_1=A_2{v}_2$
$⟹\frac{v_2}{v_1}=\frac{r_1^2}{r_2^2}$
$=\frac{1}{4}$