Do a trick with a paperclip
Does a paperclip sink or float on water? The answer is: it does both! Discover how with this trick and keep other people guessing.
Get started
Step 1
Put a paperclip in the water. Does it float or sink?
Step 2
Now put the stamp or piece of paper in the bowl of water and very carefully place the paperclip on top.
Step 3
Use the other paperclip to gently push the stamp or the piece of paper to the bottom of the bowl. Your paperclip continues to float!
Very carefully, remove the stamp or piece of paper from the bowl without touching the floating paperclip.
Show the floating paperclip to someone else and ask them to try it for themselves (without telling them the secret, of course!).
What did you discover?
Water consists of water molecules that exert a strong attractive force. The molecules on the surface have no water molecules above them. This means that they attract the water molecules beside them and below them even more strongly. We call this effect ‘surface tension’.
Because of this, objects that would not normally float on water can still lie on the surface without sinking. However, you have to place them on the surface of the water very carefully to avoid breaking the surface tension. That’s what the stamp or piece of paper is for: it helps maintain the tension so that the paperclip can ‘float’.
