Slide 1 of 15
Compared with the allure of video games, the classic toys of yore may seem boring to today's kids. But in fact, they aren't quite as mundane as they seem: Many of these toys embody important physical concepts, and playing with them helps children develop an intuitive understanding of the world around them something that cannot be gleaned from the virtual worlds of modern gaming.
To learn the underlying physics of your favorite classic toys, read on.
Spinning topsSlide 2 of 15
The spinning top, a toy found across many of the world's cultures and even among ancient archaeological ruins, lays bare some profound physical principles. The first is the conservation of angular momentum, the law that dictates that, in the absence of external influences, something spinning must keep spinning. Because a top balances upon a tiny point, it experiences a minimal amount of friction with the surface below it, and thus continues spinning for a delightfully long time, demonstrating the law.
But as friction eventually slows the top, it becomes unstable and starts to wobble, leading to the demonstration of another principle, called "precession." When the top wobbles, its axis of rotation the invisible line running vertically through its center tips sideways, making an angle with the table.
This angle allows the force of gravity to exert a "torque" on the top, putting additional spin on it, and this causes it to swing (or precess) outward in an arc, still spinning as it does so. In an effort to conserve its total angular momentum, the top precesses faster the slower it spins; this explains why tops typically lurch outward just as friction brings their spinning to a stop.Slide 3 of 15
Plasma lampsSlide 4 of 15
Plasma lamps (or globes) are beautiful visual displays of a very strange variety of matter.
These clear glass orbs are filled with a mixture of non-reactive gases such as helium, neon and krypton kept at less than one-hundredth the pressure of the outside air. The smaller sphere at the lamp's center is an electrode an electrical conductor that is used to transfer electricity from a circuit to a surrounding vacuum. When the lamp is plugged in, a high-frequency electric current flows into the electrode, and from there, passes to the gaseous atoms surrounding it. The current ionizes the atoms, giving them an electric charge and simultaneously causing them to emit flashes of light. An ionized gas is called a plasma.
Because electrons try to flow as far from one another as possible (repelled by each other's negative charges), they shoot outward from the central electrode in every direction toward the outer glass orb. Their escape routes are the plasma filaments visible in the lamps.
Placing your hand near the glass alters the electric field that exists between the central electrode and glass orb, effectively strengthens the force that draws electrons outward. This is why a plasma filament will seem to be attracted to your hand when you touch the ball. Fortunately, commercial plasma lamps are low-power enough that it doesn't hurt when the electric current passes along the filament, through the glass and into your hand.Slide 5 of 15
SlinkySlide 6 of 15
As demonstrated by University of Sydney physics professor Rod Cross in the above video, a classic Slinky toy exhibits some truly startling physics. When you hold up a Slinky, then let go, the bottom remains stationery until the rest of the coil has collapsed down on top of it. It seems to hover in the air, defying the laws of physics, before finally falling to the ground with the rest of the coil but in fact this behavior makes perfect physical sense.
"The simplest explanation is that the bottom end is sitting there minding its own business, with gravity pulling it down, and tension pulling it up equal and opposite forces," Cross said. "No motion at the bottom end, until the bottom end gets the information that the tension has changed. And it takes time for that information to propagate down through the Slinky."
In short, a compression wave, which carries information about the disappearance of the upward force, has to travel down the Slinky to the bottom end before that end "knows" that the Slinky has been dropped, and that it should fall.
What would really be physics-defying is if the bottom end of the Slinky were to fall the instant you let go of the top. This sort of "action-at-a-distance" never happens in nature.Slide 7 of 15
Drinking birdsSlide 8 of 15