# Raindrops are falling vertically at a speed of 120 km/h through air that is moving horizontally at a speed of 40 km/h(i.e. the wind is 40 km/h). At what angle do the drops strike the ground?

Oct 3, 2017

${18}^{\circ}$ from vertical or ${72}^{\circ}$ from horizontally.

#### Explanation:

Air is moving horizontally with 40 km/h speed
Horizontal velocity vector of Air is shown in figure.

Velocity Vector of Raindrops is vertically downward .
Let resulting Velocity of Raindrops makes angle $\theta$ from the
vertical.
Then angle
$\tan \theta = {v}_{\text{Horizontal"/v_"vericle}} = \frac{40}{120} = \frac{1}{3}$

$\theta = {\tan}^{-} 1 \left(\frac{1}{3}\right) \approx {18}^{\circ}$

Hence Raindrops makes angle ${18}^{\circ}$ from the vertical or make angle ${72}^{\circ}$ from Horizontal.