Make a penny dive straight down into a container of water by removing a hoop rapidly. When you pull the hoop out slowly, friction causes the penny to move with the hoop and it misses its target below. However, if you pull the hoop out very quickly, the lack of friction keeps the penny from going away with the hoop and gravity pulls it straight down.
Use a stiff strip of paper that is .75 X 12 inches and create a hoop. Arrange your penny for a high dive and watch it land in the water!