A body falls freely from the top of a tower and during the last second of its fall, it falls through 25 m. Find the height of tower.
Solution: Here,
Initial velocity (u)=0 ms^-1
Height fallen in (Tth) last second (S1)= 25 m
Height of tower ( h)=?
Using the formula for nth second,

[tex]st = u + \frac{a}{2} (2t - 1)[/tex]
[tex]or \: 25 = 0 + \frac{10}{2} (2t - 1)[/tex]
[tex]or \: 25 = 10t - 5[/tex]
[tex]or \: 10t = 30[/tex]
[tex]therefore \: \: \:t = 3sec[/tex]
[tex]so \: height \: of \: the \: tower[/tex]
[tex]h = ut + \frac{1}{2} {gt}^{2} [/tex]

[tex] = 0 + \frac{1}{2} \times 10 \times 9[/tex]
[tex] = 45m \: [/tex]







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