Observations and results
Why do you think the coin acted differently when you pulled the loop off slowly and when you swiped the loop away quickly?
The coin isn't acting out—it's obeying the laws of physics. When the loop it is resting or is pushed over slowly, it stays with the loop longer because friction helps keep it there. Then gravity eventually takes over and the coin tumbles down to the counter. But when the paper surface it has been resting on is swiped out from under it quickly, the friction doesn't have a chance to pull it along. Instead, the coin, which was at rest, has nowhere to go but straight down with the force of gravity.
Share your coin drop observations and results! Leave a comment below or share your photos and feedback on Scientific American's Facebook page.
Pour out the water, being careful not to lose any coins down the drain. Recycle or reuse your container.
More to explore
"What's the real story with Newton and the apple? See for yourself" from Scientific American
"How Much Momentum Does It Take to Stop a Running Back?" from Scientific American
"Newton's First Law" overview from NASA's Kid's Page
"Newton's Laws of Motion" overview from TeacherTECH
Gravity Is a Mystery by Franklyn M. Branley, ages 4–8
The Everything Kids' Science Experiments Book: Boil ice, float water, measure gravity—challenge the world around you! by Tom Robinson, ages 9–12
Bend Water with Static Electricity
What you'll need
• Three small Styrofoam cups (alternatively, you can use two paper cups to hold the water and an inflated balloon to provide the static charge)
• Someone with a head of clean, dry hair