MCQ
If the water falls from a dam into a turbine wheel $19.6\, m$ below, then the velocity of water at the turbines, is .................. $\mathrm{m} / \mathrm{s}$ (take $g = 9.8\, m/s^2$)
- A$9.8$
- ✓$19.6$
- C$39.2$
- D$98$
✓
Answer
Correct option: B.
$19.6$
b
${v^2} - {u^2} = 2as \Rightarrow {v^2} - {0^2} = 2 \times 9.8 \times 19.6$
${v^2} - {u^2} = 2as \Rightarrow {v^2} - {0^2} = 2 \times 9.8 \times 19.6$
(Initial velocity $= 0$ as water falls from rest)
$\begin{array}{l}
\Rightarrow \,v = \sqrt {2 \times 9.8 \times 2 \times 9.8} \\
\,\,\,\,\,\,\,\,\,\, = 2 \times 9.8 = 19.6\,m/s
\end{array}$
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