Here the AEM is used to investigate the effects of springs, ropes and gravity on a car trunk mechanism. When the trunk is in the closed position, the springs are in maximum compression, but all their force is directed parallel to the trunk. Hence, when the trunk is opened slightly and released, it closes under gravity.
However, when the trunk is lifted beyond a certain point, the spring force has a large enough component perpendicular to the trunk to overcome gravity. This time, when the trunk is released it rises. The animation also illustrates the use of ropes to simulate the lifting of a luggage flap within the trunk space.
Using the AEM, it is easy to investigate the equilibrium point at which the springs take effect. Modifications can be made to the location and strength of the springs, and the resulting change in behaviour can be seen immediately.