A body falling from a high mimaret travels 40 meters in the last 2 seconds of its fall to ground. Height of minaret in meters is (take `g=10(m)/(s^2)`)

Options

A. 60
B. 45
C. 80
D. 50

Answer

B

Explanation

Height of minaret, `H = 1/2 g t^2`
In last 2sec body travels distance of 40m
`(H-40) = 1/2 g (t-2)^2`
`rArr H - 40 =1/2 g t^2 - 2gt + 2g`
`rArr H - 40 = H - 2g t + 2g`
`rArr t = 60/20 = 3sec`
`rArr H = 1/2 xx 10 xx (3)^2 = 45m.`