Watch this amazing video of a childrens toy appearing to defy the laws of gravity.
Although the bottom of the slinky appears to hover in space and defy gravity, the laws of physics are not actually being violated. In fact the stretch of the spring exerts an upward force on the lower weight. Before the spring is released, the weight of the lower mass stretches the spring. Gravity pulls on the lower mass. The stretch of the spring pulls up equal and opposite on the lower mass. The result is zero force on the lower mass. When the top of the spring is released, the spring is still stretched. The stretching force continues to pull up on the lower mass equal to the lower mass’s weight. Gravity and the stretch of the spring continue to cancel each other and the lower weight remains suspended.
Pretty freaky eh?