An object is dropped from the top of a tower. It travels a distance 'x' in the first second of its motion and a distance '7x' in the last second. Height of the tower is: (Take `g = 10 m//s^(2)`)

Options

A. 60 m
B. 70 m
C. 80 m
D. 90 m

Answer

C

Explanation

`x = (1)/(2) xx g(1)^(2) " " x = 5m`
`35 = (1)/(2) xx g [2 t -1] " " t = 4 sec`
Hence, Height of tower, `H = (1)/(2) xx 10 xx t^(2) = 80 m`