A ball is dropped from a height of $90 ext{ m}$ on a floor. How much time does it take to hit the f

Question

A ball is dropped from a height of $90	ext{ m}$ on a floor. How much time does it take to hit the floor for the first time? (Take $g = 9.8	ext{ m/s}^2$)

Professor PC Thomas Classes · Answer

Using $h = \frac{1}{2}gt^2$, $t = \sqrt{\frac{2h}{g}} = \sqrt{\frac{2 	imes 90}{9.8}} = \sqrt{\frac{180}{9.8}} \approx 4.28	ext{ s}$.