Question

A particle is dropped from a tower. It is found that it travels 45 m in the last second of its journey. Find out the height of the tower? (take g =10 $m/s^2$)

• A. 25 m
• B. 100 m
• C. 125 m
• D. 150 m

Answer 1

Answer: (C)

125 m

Let the total time of journey be n seconds.
Distance travelled in nth sec;

$s_n=u+\frac{a}{2}(2n-1)\Rightarrow 45=0+\frac{10}{2}(2n-1)$
$n=5sec$
Height of tower; $h=\frac{1}{2}g{t}^2=\frac{1}{2}\times 10\times 5^2=125m$