A thin rod of length `1 m` is fixed in a vertical position inside a train, which is moving horizontally with constant acceleration `4 ms^(-2)`.A bead can slide on the rod and friction coefficient between them is `0.5`. If the bead is released from rest at the top of the rod , it will reach the bottom in

Explanation

From force diagram of bead

`N = ma_(0) = 4 m`
`mg - mu N = ma`
`or mg - (1)/(2) 4m - ma`
`or 10m - 2m = ma rArr a = 8 ms^(-2)`
`L = (1)/(2)at^(2) or 1 = (1)/(2) xx 8 xx t^(2) or t^(2) = (1)/(4)`
`:. t = (1)/(2)s`