Question

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

• A. $125m$
• B. $180m$
• C. $100m$
• D. $55m$

Answer 1

The correct option is A $125m$

Given,

$s=45m$

$a=g$

Distance travelled in last second

$S=u+a(n-\frac{1}{2})$

$45=0+10(n-\frac{1}{2})$

$n=4.5+0.5$

$n=5thsecond$

Total time of flight is $5$ seconds

Height of the tower

$H=0.5g{t}^2$

$=0.5\times 10\times 5^2=125m$

Hence, height of the tower is $125m$.