Applet shows an object moving down the smooth surface of a wedge. The wedge itself is free to slide on a smooth horizontal surface. The red dots show the postions of some reference point on the moving object at regular intervals of time. The red vector represents the acceleration of the wedge, the yellow vector represents the accelration of the object and the white vector, the accelration of the object relative to the wedge. It is possible to vary the mass ratio of the object and the wedge. Experiment to see the relation between the accelration vectors.