Question

A girl standing on road holds her umbrella at $45^{\circ}$ with the vertical to keep the rain away. If she starts running without umbrella with a speed of $15 \sqrt{2} \,kmh ^{-1}$, the rain drops hit her head vertically. The speed of rain drops with respect to the moving girl is :

• A. $30\, k m \,h^{-1}$
• B. $\frac{25}{\sqrt{2}} \,k m \,h^{-1}$
• C. $\frac{30}{\sqrt{2}} \,k m\, h^{-1}$
• D. $25\, km\,h ^{-1}$

Answer 1

Answer: (C)

$V =\tan \theta=\frac{V_{G}}{V_{R G}}$
$1=\frac{V_{G}}{V_{R G}} \Rightarrow 15 \sqrt{2}=V_{R G}$