Question

A body is dropped from a height $39.2m$. After it crosses the half distance, the acceleration due to gravity ceases to act. Then the body will hit the ground with a velocity of (Take $g=9.8m{s}^{-2}$)

• A. $19.6m{s}^{-1}$
• B. $20m{s}^{-1}$
• C. $1.96m{s}^{-1}$
• D. $196m{s}^{-1}$

Answer 1

The correct option is A $19.6m{s}^{-1}$

Given that,

Height $h=39.2m$

Initial velocity $u=0$

Now, from equation of motion

After crosses half distance, the acceleration due to gravity ceases to act

So,

$h=\frac{39.2}{2}$

$h=19.6m$

$v^2-u^2=2gh$

$v^2=2\times 9.8\times 19.6$

$v=19.6m/s$

Hence, the velocity is $19.6m/s$