Question

A man standing on the road has to ho!d his umbrella at ${30}^o$ with the vertical to keep the rain away. He throws the umbrella and starts running at $10km/hr$ . He find that rain drops are hitting his head vertically, then the speed of the rain drops with respect to moving man.

• A. $20km/hr$
• B. $10\sqrt{3}km/hr$
• C. $\frac{10}{\sqrt{3}}km/hr$
• D. $10km/hr$

Answer 1

Answer: (B)

$10\sqrt{3}km/hr$

The angle of rain is given as,

$\theta ={30}^{\circ }$

The horizontal component of the rain is given as,

$v_x=10km/h$

The vertical component of rain is given as,

$\frac{v_x}{v_y}=\tan {30}^{\circ }$

$v_y=10\sqrt{3}km/h$

Thus, the speed of rain drops with respect to moving man is $10\sqrt{3}km/h$.