A bird files between two trains approaching each other with constant speed of 10 m/s each. Trains are initially 1 km apart. The bird starts from the first train and as it arrives just in front of the other train it turns and continues the same process. The average velocity of the bird till it is sandwiched between the trains is:

Two trains start simultaneously from two stations Howrah and Bandra, respectively towards each other on the same track. The distance between the two stations is 560 km and the speed of trains are 30 and 40 km/h. Simultaneously with the trains, a sparrow sitting on the top of one of the train starts towards the other and reverses its direction on reaching the other train and so on. If the speed of sparrow is 80 km/h then the distance that the sparror flies before being crushed between the train is :

Two train are moving in a straight line in the same direction with a speed of 80 km/h. The relative velocity of one trains w.r.t. each other is