The ratio of distances travelled by a body starting from rest with constant acceleration in `g^(th) and 8^(th)` second is .........

Options

A. `17/15`
B. `8/9`
C. `15/17`
D. `9/8`

Answer

A

Explanation

Distance covered by particle in `n^(th)` second,
`x _(n) = v _(0)+ a/2 (2n -1)`
`therefore` Distance coverd in `9^(th)` second,
`x _(9) =(a)/(2) (2 (9) -1) = (17a)/(2) (because v _(0) =0)`
Distance covered in `8^(th)` second,
`x _(8) = a/2(2 (8) -1) = (15a )/(2)`
`therefore (x _(9))/(x _(8)) = (17a)/(2) xx (2)/(15 a)= (17)/(15)`