Question

A stone falls from a balloon that is descending at a uniform rate of $12\text{m/s}$. The displacement of the stone from the point of release after $10\text{sec}$ is

• A. $490\text{m}$
• B. $510\text{m}$
• C. $610\text{m}$
• D. $725\text{m}$

Answer 1

The correct option is C $610\text{m}$

Since, the balloon is descending and a stone falls from it, the stone will be having same initial velocity as that of balloon i.e. $u=-12\text{m/s}$
$a=g=-9.8{\text{m/s}}^2,t=10\text{sec}$
From equation of motion we have,
$S=ut+\frac{1}{2}a{t}^2$
$\Rightarrow -h=-12\times 10-\frac{1}{2}\times 9.8\times (10{)}^2$
$\Rightarrow -h=-120–490$
$\Rightarrow -h=-610m$
$\Rightarrow h=610m$
Hence, displacement of stone is $h=610m$