Question

At $t=0$, a stone of mass $10\, g$ 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 $1^{st}$ stone from the ground level at that moment?
(take $g =10 \,m / s 2$ )

• A. 10 m
• B. 1 m
• C. 2m
• D. 5 m

Answer 1

Answer: (D)

Distance covered in $1\, s$
$h=u t-\frac{1}{2} g t^{2} $
$=10 \times 1-\frac{1}{2} \times 10 \times 1^{2} $
$=10-5=5\, cm$
So, the position of $1^\text{st}$ stone from the ground is $5 \,m$.