Question

A ball is released from the top of a tower of height $h$ metre. It takes T seconds to reach the ground. What is the height of the ball from the ground after $\frac{T}{3}$ second?

• A. $17h/9$ from the ground
• B. $8h/9$ from the ground
• C. $7h/9$ from the ground
• D. $h/9$ from the ground

Answer 1

The correct option is B $8h/9$ from the ground

For free fall $H=g{t}^2/2$

Put $H=h$ we should get time as $t=T$ so $T^2=2h/g$..................... 1

put $t=T/3$ in eqaution-1 we get

$H=\frac{g(T/3{)}^2}{2g}=g{T}^2/18g=h/9$

This $H$ is displacement from initial point i.e height fall from top point so height from the ground will be $h-h/9=8h/9$

Option B is correct.