# Question #26ccf

Aug 2, 2016

$n = 1$

#### Explanation:

$h = u t + \frac{1}{2} g {t}^{2}$.
$u \mathmr{and} t$ are initial velocity and time of fall to reach ground respectively.

• Height of $9 t h$ storeys of the building $h$, is found by inserting given values
$h = 0 \times 3 + \frac{1}{2} \times 10 \times {3}^{2} = 45 m$
Height of each storey$= \frac{45}{9} = 5 m$

• Height dropped in first second is
${h}_{1} = 0 \times 3 + \frac{1}{2} \times 10 \times {1}^{2} = 5 m$

• Now height dropped in first second $5 m$
$= n \times \text{height of each storey}$
$\implies n = 1$