Question

A wagon is coasting at a speed vA along a straight and level road. When twenty-five percent of the wagon's mass is thrown off the wagon, parallel to the ground and in the forward direction, the wagon is brought to a halt. If the direction in which this mass is thrown is exactly reversed, but the speed of this mass relative to the wagon remains the same, the wagon accelerates to a new speed vB. Calculate the ratio vB/vA.