Q. A balloon is at a height of $81\ m$ and is ascending upwards with a velocity of $12\ m/s$ . A body of $2kg$ weight is dropped from it. If $g = 10\ m/s^{2}$, the body will reach the surface of earth in
A) $1.5\ s$
B) $4.025\ s$
C) $5.4\ s$
D) $6.75\ s$
Explanation
(c) $h = ut + \frac{1}{2}gt^{2} \Rightarrow 81 = - 12t + \frac{1}{2} \times 10 \times t^{2} \Rightarrow t = 5.4\ sec$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.