Q. A ball is projected horizontally with a velocity of $5\ m/s$ from the top of a building $19.6\ m$ high. How long will the ball take to hit the ground
A) $\sqrt{2}\ s$
B) $2\ s$
C) $\sqrt{3}\ s$
D) $3\ s$
Explanation
(b) [image:4_image167.emf]
Let $t\ s$ be time taken by the ball to hit the ground
$\therefore H = \frac{1}{2}\ gt^{2} \Rightarrow t = \sqrt{\frac{2H}{g}} = \sqrt{\frac{2 \times 19.6m}{9.8\ ms^{- 2}}} = 2s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.