Q. A body of mass 3 kg falls from the multi-storeyed building 100m high and buries itself 2m deep in the sand. The time of penetration will be
A) 0.09 s
B) 0.9 s
C) 9 s
D) 10 s
Explanation
(a) $v = \sqrt{2 \times 9.8 \times 100} = \sqrt{1960}ms^{- 1}$
$\frac{\sqrt{1960} + 0}{2} = \frac{2}{t}$ or $t = \frac{4}{\sqrt{1960}}$s =$\frac{4}{44.27}$s =0.09s
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.