Properties Of Solids And Liquids Question 235
Question: Velocity of water in a river is[CBSE PMT 1988]
Options:
A) 2
B) 3
C) 4
D) $ 2\sqrt{2} $
Show Answer
Answer:
Correct Answer: C
Solution:
$ t=\frac{A}{a}\sqrt{\frac{2}{g}}\left[ \sqrt{H _{1}}-\sqrt{H _{2}} \right] $
Now, $ T _{1}=\frac{A}{a}\sqrt{\frac{2}{g}}\left[ \sqrt{H}-\sqrt{\frac{H}{\eta }} \right] $
and $ T _{2}=\frac{A}{a}\sqrt{\frac{2}{g}}\left[ \sqrt{\frac{H}{\eta }}-\sqrt{0} \right] $ A
ccording to problem $ T _{1}=T _{2} $ $ \sqrt{H}-\sqrt{\frac{H}{\eta }}=\sqrt{\frac{H}{\eta }}-0 $
therefore $ \sqrt{H}=2\sqrt{\frac{H}{\eta }}\Rightarrow \eta =4 $
