A passenger is travelling a train moving at 40 ms-1.His suitcase is kept on the berth. The driver of trainapplies breaks such that the speed of the traindecreases at a constant rate to 20 ms-1 in 5 s. Whatshould be the minimum coefficient of friction betweenthe suitcase and the berth if the suitcase is not toslide during retardation of the train?
Answer :- b
Solution :- Retardation of train =204 = 5ms2
it act in the backward direction friction force on suitcase 5m newton , where m is the mass of suitcase 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 = mmg or m = 5/10
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