Question

Brandon Stark saw some suspicious activity at the terrace of a tower. When he reached there, he saw some thieves and hurried back to tell his father. Accidentally, he fell from the top of the tower and landed on the ground exactly 2 seconds later. Find the height of the tower. $g=10m{s}^{-2}$

• A. 5 m
• B. 10 m
• C. 15 m
• D. 20 m

Answer 1

The correct option is D

20 m

Brandon experienced a free fall from the top of the tower and, thus, was under the acceleration due to gravity $g=10m{s}^{-1}$.
Let $s$ be the distance travelled, $u$ be the initial velocity, $t$ be the time taken.
Distance travelled in $t=2s$ can be found out by applying equation of laws of motion :
$s=u\times t+\frac{1}{2}\times g{t}^2$
Since he fell from rest, u = 0
$s=\frac{1}{2}\times g{t}^2=\frac{1}{2}\times 10\times 2^2=20m$