Try these experiments and see what happens. Then try to guess why it happens. Compare your results to the results at the bottom of this page.
How? Bend a paperclip into an "L" shape. Use this clip to gently lay another paperclip on the top of the water in a glass. What happens? Why?
How? Place an empty soda pop bottle in the freezer for at least an hour. Remove the bottle from the freezer and wet the top. Grasp the sides of the bottle, and wait. What happens? Why?
How? Fill a bottle with hot water and a bowl with cold water. Let them sit for one minute, then empty the bottle. Stretch a balloon over the open end of the bottle and immerse the bottle in the cold water. What happens? Why?
How? Tie a string in a loop and slip it over a ruler. The other end should twist into a loop and slide over the handle of a hammer resting at the end of its rubber grip. Place the ruler's edge with the hammer head underneath on the edge of a table. The hammer handle should rest against the other end of the ruler. What happens? Why?
How? Fill a plastic jar with rice, carefully jab a knife into the rice five or ten times. The rice will settle a bit, then add more rice. Continue until no more rice can be added. Then quickly jab the knife into the rice and lift. What happens? Why?
How? Fill a glass three-quarters full with water. Place a handkerchief over the top of the glass and hold it on with a rubberband place around the rim of the glass. Push down on the center of the handkerchief until it touches the water (the experiment works best if the handkerchief is slightly wet). Keep your fingers pressed on the handkerchief and turn the glass upside down. The water will remain in the glass. Now, pull the handkerchief tight, so that the concave shape disappears. What happens? Why? Is it really "boiling"?
Why Does the Paperclip Float? The surface of the water bends around the weight of the paperclip like stretched rubber. This is because water has surface tension.
Why Does the Penny Pop? Your hands warm the air inside the bottle which then expands. It can only escape by moving the penny and cracking the ice around the rim. The build up and release of air causes the popping, as long as ice remains between the penny and bottle.
Why Does the Balloon Inflate in the Bottle? The warm water heats the bottle which, in turn, heats the air inside the bottle after the water is poured out. When the bottle is placed in the cold water, the air inside cools and contracts, causing outside air to be drawn in, pulling the balloon in and inflating it inside the bottle.
Why Does the Hammer Balance on the Edge of the Table? All objects have a center of gravity that acts as if all the weight of the object were balanced there. The center of gravity of the ruler is in the middle, but the hammer moves the center of gravity of the system to under the table's edge which keeps it from falling.
Why Are You Able to Pick Up the Jar of Rice With the Knife? The rice gets more and more packed down by repeated stabs from the knife until the rice is so compact that it presses against the blade of the knife with enough force to overcome the pull of gravity on the jar.
Why Does the Water Appear to Boil Without Heat? Surface tension prevents the water from seeping through the handkerchief. When you straighten out the handkerchief, the water drops down to a new level, reducing the pressure in the air space at the "bottom" of the glass. The higher air pressure outside the glass forces air to penetrate the handkerchief and bubble through the water. But it's not really boiling!