Physics

Steve Carabello

Most people have misconceptions about the way the world works -- even when confronted with reality, they say "that can't be right." (It's even been proved by a research study that this confusion is caused by "your brain... clinging to misconceptions about science.") Here are some sample video clips and animations that do match reality, but run counter to most people's intution. Do you want to know why they work that way? Ask me a question, or read a physics textbook.

From Wake Forest University:
• Bicycle wheel angular momentum demo
• "Feeble-minded disk:" having a (hidden) mass off-center can make it possible for something to roll uphill.
• Balancing Bird: only the center of mass needs to be supported.
• Balance Stick: it can take many masses on one side to balance a single mass on the other, depending on where they are.
• The classic Newton's Cradle
• Double Ball Bounce: with energy and momentum nearly conserved for a tennis ball on a basketball, a surprisingly high bounce can be achieved.

From The University of Iowa:
• Ball in a water stream: Read up on Bernoulli's Equation.
• Ball in an air stream: Even more on Bernoulli's Equation.

From The University of Minnesota:
• Reversible Process: Yes, some of these do exist, though they are rather rare.
• Pull carts: Even with just one person pulling, both people move.
• "Wine Butler"
• "Hinged Stick Paradox"
• Block and cylinder: stable and unstable
• "Walking" a spool in both directions, pulling on the string both times.
• Suitcase Gyroscope
• Bicycle wheel precession
• Rotating stool and weights
• Leaky Boats: Surface tension can be enough to keep things afloat.
• Floating Beach Ball: Another use of Bernoulli's Equation.
• Ball and Funnel: Yet another use of Bernoulli's Equation.
• Vacuum Bazooka: Atmospheric pressure is strong enough to blast a ping-pong ball through a soda can.
• Crush the Soda Can: The differece in pressure between atmospheric pressure and pressure in a cooled soda can is enough to crush it.
• Deflection of Water Stream Water is attracted to charged objects.
• Kelvin Water Dropper: These can be used to create a large voltage.
• Magnet in slow fall: Induced currents create surprisingly strong forces.
• LN₂ Cooled Copper Plate and Magnet:A strong magnet sits on a cooled copper sheet. Clearly, the induced currents set up fields that tend to oppose any changes in magnetic field.
• Finger in Beaker: Buoyant forces

Linked from the High Field Magnet Laboratory (HFML):
• Superconducting Levitation: The Meissner Effect.
• Superconducting Levitation: watching a magnet float and spin.
• Diamagnetic Levitation: Movies. A list of interesting movies, including Weightless Water, Kissing Droplets, The Levitating Strawberry, and The Flying Dutchfrog.

From Hyperphysics:
• Van de Graaff Generator: using static electric repulsion for lots of interesting things, including: hair standing on end, puffed wheat spray, lighting a fluorescent bulb, and repelling soap bubbles.
• Atmospheric pressure: crushing a steel drum: using cooling steam in a sealed container to crush a 50-gallon drum.
• Atmospheric pressure: crushing a steel drum with an aspirator on a faucet: The difference in pressure due to moderately-flowing water can have some surprisingly strong effects.
• Pascal's principle: dropping the bottom out of a bottle.
• Rijke tube: resonating an open pipe with a flame
• Kundt tube: longitudinal standing waves in air generated by stroking a metal rod.

From the Journal of Chemical Education: Chemistry Comes Alive!
• Ferrofluid. A quick internet search should lead you to quite a few other very interesting videos.
• Ice Bomb: Since water near the freezing point expands as it cools, you can get tremendous outward forces.
• Dust Explosion in a Metal Can: anything that is even somewhat flammable, when it has a large surface area exposed to Oxygen (such as a powder surrounded by air) can become explosive.

From Journal of Chemical Education: Chemistry Comes Alive!
• Bill B. Science Videos. See especially the explanation for the "Bottle Smash!" "High voltage 'Air Threads'" "Tesla Coil as a vacuum pump" "Dangerous High-speed Magnetic Levitation" etc.

Things I plan to add links to (Until then, search the internet for these topics, for some interesting stuff.)
• Chladni Plates.
• Fresnell's Bright Spot.
• Holography.
• Tesla Coils.
• Low Delta-T Stirling Engines.
• Thermoacoustics
• Coriolis forces and rotating reference frames.
• Superheating/supercooling.
• Non-Newtonian fluids
• Diamagnetic Levitation with graphite sheets

Page last modified: Tuesday, 06-Nov-2007 18:59:02 EST