The figure shows a square train wagon ABCD which has a smooth floor and side length of 2 L. The train is mov- ing with uniform acceleration (a) in a direction parallel to DA. A 'ball is rolled along the floor with a veloci- ty u, parallel to AB, with respect to the wagon. The ball passes through the centre of the wagon floor. At the instant it is at the centre, brakes are CD AB u 2 L 2 Lapplied and the train begins to retard at a uniform rate that is equal to its previous acceleration (a)
(a) Will the ball hit the wall BC or wall CD or the corner C?
(b) What is speed of the ball, relative to the wagon at the instant it hits a wall ?

Answer

(a) Corner C (b) u