When Wile E. Coyote attaches a balloon to an anvil, as he pushes the anvil across the outcropping, it appears to be quite heavy. However, as soon as he pushes it off the edge, the anvil (after a small drop) floats quite easily, and, in fact, rises above the level of the outcropping. The anvil should have been floating away as he pushed it to the edge of the outcropping.