Q. At $t = 0$, a stone of mass $10\ gm\ $ is thrown straight up from the ground level with a speed $10\ m/s$. After $1\ s$, a second stone of the same mass is thrown from the same position with a speed $20\ m/s$. What is the position of the first stone from the ground level at that moment? (Take $g = 10\ m/s^{2}$)
A) $10\ m$
B) $1\ m$
C) $2\ m$
D) $5\ m$
Explanation
(d) $h = ut - \frac{1}{2}gt^{2}$
$= 10 \times 1 - \frac{1}{2} \times 10 \times 1$
$= 10 - 5 = 5m$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.