Question

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

• A. $\frac{17 h}{18}$ metre from the ground
• B. $\frac{8 h}{9}$ metre from the ground
• C. $\frac{7 h}{9}$ metre from the ground
• D. $\frac{h}{9}$ metre from the ground

Answer 1

Answer: (B)

$\Rightarrow h=\frac{1}{2}gT^{2}$
or $T = \sqrt{\frac{2 h}{g}}$
Now, $S = \frac{1}{2} g \left(\right. \frac{T}{3} \left.\right)^{2} = \frac{g}{18} \times \frac{2 h}{g} = \frac{h}{9}$
Height above the ground $= h - \frac{h}{9} = \frac{8 h}{9}$