A body falls from rest. In the last second of its fall, it covers half of the total distance then the total time of its fall is

Options

A. `(2-sqrt(2))s`
B. `(2+sqrt(2))`s
C. 2 s
D. 4s

Answer

b

Explanation

Let be total disatnce covered in n second
s/2 =0 +g/2(2n-1)
s=g(2n-1)=9.8(2n-1)
Also `s=0+(1)/(2)gn^(2)=4.9n^(2)`
`:. 9.8(2n-1)=4.9n^(2)`
or `n^2 -4n+2=0`
Solving the quadrtic equation,
`n=(2+sqrt(2))` second.