A passenger is traveling a train moving at `40 ms^(-1)` Hit suitcase is kept on the berth ,The drive of train applies breaks such that the speed of the train decreases at a constant rate to `20 ms^(-1)` in `5s` What should be the minimum coefficient of friction between the suitcase and the berth if the suitcase is not to slide during and retardation of the train ?

Options

A. `0.3`
B. `0.5`
C. `0.1`
D. `0.2`

Answer

b

Explanation

Retardation of train `= 204 = 5 ms^(_2)`
it act in the backward direction friction force on suitcase `5m` newton , where `m` is the mass of suicase in acts in the forward direction due to this force the suitcase has a tendency to slide forward if suitcase is not to slide then `5m` = force f of friction
or ` 5m = m mg or m = (5)/(10) = 0.5`