Question

A car with a vertical windshield moves in a rain storm at a speed of $40\, km / hr$. The rain drops fall vertically with constant speed of $20\, m / s$. The angle at which rain drops strike the windshield is

• A. $\tan ^{-1} \frac{5}{9}$
• B. $\tan ^{-1} \frac{9}{5}$
• C. $\tan ^{-1} \frac{3}{2}$
• D. $\tan ^{-1} \frac{2}{3}$

Answer 1

Answer: (A)

$\tan \theta=\frac{v_{m}}{v_{r}}=\frac{\frac{20 \times 5}{9}}{20}$
$\theta=\tan ^{-1}\left(\frac{5}{9}\right)$