question_answer

A passenger is travelling a train moving at \[40\,m{{s}^{-1}}\]. His suitcase is kept on the berth. The driver of train applies breaks such that the speed of the train decreases at a constant rate to \[20\,m{{s}^{-1}}\] in 5 s. What should be the minimum coefficient of friction between the suitcase and the berth if the suitcase is not to slide during retardation of the train?

Answer:

0.5