How's that possible?
Mighty Morphin Power Finger
How are you able to keep your friend from standing with just one finger?
Answer: center of gravity (or center of balance). Center of gravity is the point where the weight of an object is equally balanced. When you’re sitting, your center of gravity is in your hips. You must lean forward or use your hands in order to shift the center of gravity to your knees. In doing so, you’re giving your legs the balance and strength you need in order to stand up. In the experiment, your subject cannot use his hands and your finger prevents him from leaning forward. So he is unable to shift his center of gravity from his hips to his knees and, therefore, unable to stand.
Why does the pepper scurry to the edges of the bowl?
Answer: surface tension. Surface tension is due to water molecules sticking together like a skin. Surface tension makes it possible for some insects to walk on water and for pepper to float in the bowl. When a drop of soap is added to the water, it weakens the surface tension and the water pulls away from the soap, moving the pepper along with it!
The Hokey Pokey Leak-proof Bag
Why doesn't the bag leak when you stick pencils through it?
Answer: polymers. Plastic is composed of long chains of molecules called polymers. There are all sorts of polymers that form all sorts of materials including tires, silk, Styrofoam cups, and acrylic paint. The polymers in plastic bags, for example, are strong and stretchy. When you poke a pencil through the bag, first the plastic stretches and then the polymers form a watertight seal around the pencil. Too bad wooden boats aren't made up of these kinds of polymers!
Don't Mess with Slimeman
Why does the slime drip like a liquid when you hold it in the palm of your hand but feel like a solid when you squeeze it?
Answer: it's a non-Newtonian fluid. Non-Newtonian fluids, like quicksand, have both liquid and solid properties. When you combine water and corn starch, the water molecules flow between the corn starch molecules. If you squeeze the slime, it feels like a solid because you are applying pressure, which slows the flow of water molecules. On the other hand, if you don't apply pressure to the slime, it flows like a liquid. That's because the water molecules can move easily between the corn starch molecules.