The Garibrath express can move at 45 km./hr. without its rake and the speed is diminished by a constant that varies as the square root of the number of wagons attached. If it is known that with 9 wagons, the speed is 30 km./hr., what is the greatest number of wagons with which the train can just move?

Two trains are moving in the same direction at speed of 54 km/h and 92 km/h, their lengths are 400 m and 360 m respectively. What is the time taken (in seconds) by faster train to cross the slower train?

Two towns A and B are 170 km apart, a train starts at 9 a.m. from A towards B at a speed of 40 km/hr, at 11 a.m. another train starts from B towards A at a speed of 50 km/hr. When will the two trains meet?

 A 450 meter long train crosses a bridge 650 meters long in 36 seconds. What is speed (in km/hr) of the train? 

Excluding stoppages, the speed of a train is 120 kmph and including stoppage, it is 50 kmph. For how many minutes does the train stop per hour?