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 equal distance in the 5th second, after the start of A, then the ratio the 5th second, after the start of A, then ratio `a_(1) : a_(2)` is equal to

Options

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

Answer

a

Explanation

For A, `S_(5) = 0 + a_(1) [(2 xx 5) -1]//2 = 9a_(1)//2`
for B, `t = 5-3 = 2` second, `S_(3) = O + (a_(2)//2)`
`[(2 xx 3)-1] = 5a_(2)//2`
`S_(5) = S_(3), 9a_(1)//2, a_(1) : a_(2) = 5 : 9`