A body `A` starts from rest with an acceleration `a_1`. After `2` seconds, another body `B` starts from rest with an acceleration `a_2`. If they travel equal distances in the `5^(th)` second, after the start of `A`, then the ratio `a_1 : a_2` is equal to :

Options

A. `5:9`
B. `5:7`
C. `9:5`
D. `9:7`

Answer

1

Explanation

For A
`S_(5)=(a_(1))/(2)(2xx5-1)`
For B
`S_(3)=(a_(2))/(2)(2xx3-1)`
Given that
`(a_(1))/(2)(2xx5-1)=(a_(2))/(2)(2xx3-1)`
`9a_(1)=5a_(2)`