question_answer

A body falling from a high Minaret travels 40 meters in the last 2 seconds of its fall to ground. Height of Minaret in meters is (take \[g=10m/{{s}^{2}}\])                                   [MP PMT 2002]

A)             60       

B)             45

C)             80       

D)             50

Correct Answer: B

Solution :

                Let height of minaret is H and body take time T to fall from top to bottom.             \[H=\frac{1}{2}g{{T}^{2}}\]                                 ?(i)                 In last 2 sec. body travels distance of 40meter so in \[(T-2)\]sec distance travelled \[=(H-40)\ m\].             \[(H-40)=\frac{1}{2}g{{(T-2)}^{2}}\]                               ?(ii)             By solving (i) and (ii) \[T=3\]sec and \[H=45\ m\].