A train of trucks each having a mass of 3 tons and each containing a payload of 5 tons is hauled down a gradient of 1/100 by a locomotive having a mass of 10 tons, If the rolling resistance of the train and locomotive is 110 N/ton and the coefficient of adhesion is 0,25, de termine :- (a) the number of empty trucks that can be hauled up the gradient under these conditions, allowing for an acceleration of 0,1 m/s2, and (b) the shortest distance in which the same train with loaded trucks can be stopped when travelling down-grade at a speed of 15 km/h, if the locomotive only is equipped with brakes