physics demonstration


Pascal’s Law tells us that pressure in a fluid depends on the height and density of the fluid. This is something that you’ve experienced firsthand if you’ve ever tried to dive in deep water. The deeper into the water you swim, the greater the pressure you feel, especially in your ears. Go deep enough and the pressure difference between your inner ear and the water becomes outright painful. 

In the video demonstration above, you’ll see how a tall, thin tube containing only 1 liter of water is able to shatter a 50-liter container of water. Not only does this show just how powerful height is in creating pressure in a fluid, but it shows how a fluid can be used to transmit pressure over a distance – one of the fundamental principles of hydraulics! (Video credit: K. Visnjic et al.; submitted by Frederik B.)

Behold, Physics!

In this stunning demonstration, the Myth-busters fired a soccer ball at 50 mph out of a cannon on a truck riding at 50 mph in the opposite direction. 

The ball just falls down as if it is free falling!! This is a consequence of the fact that in Newtonian mechanics, opposite vector quantities cancel out each other. You probably have heard that a legion times, but here’s the visual proof.

Sometimes I feel that textbooks butcher elegant concepts by excluding visuals during the explanation. But again, if one could incorporate gifs onto books the world would definitely be a better place. :)


This video demonstrates one of my favorite effects: the reversibility of laminar flow. Intuition tells us that un-mixing two fluids is impossible, and, under most circumstances, that is true. But for very low Reynolds numbers, viscosity dominates the flow, and fluid particles will move due to only two effects: molecular diffusion and momentum diffusion. Molecular diffusion is an entirely random process, but it is also very slow. Momentum diffusion is the motion caused by the spinning inner cylinder dragging fluid with it. That motion, unlike most fluid motion, is exactly reversible, meaning that spinning the cylinder in reverse returns the dye to its original location (plus or minus the fuzziness caused by molecular diffusion). 

Aside from being a neat demo, this illustrates one of the challenges faced by microscopic swimmers. In order to move through a viscous fluid, they must swim asymmetrically because exactly reversing their stroke will only move the fluid around them back to is original position. (Video credit: Univ. of New Mexico Physic and Astronomy)

Originally posted by clintbarthon

Imagine you are a new meta-human and you meet the Flash

“So, you are this red streak I have heard so much about.” You say as you circle around the man in the red suit. “Look, I don’t want to hurt you, so leave me alone!”

“I’m here to help you.” He takes a step towards you and before you realize it, he is right in front of you. 

“Why? We don’t even know each other.”

“I go by the Flash, and I am a meta-human, like you. I have the ability to run really fast.” You stare at him for a moment, not sure if you should trust him, but you look in his eyes and something inside of you relaxes.

“I can defy the laws of physics.” You demonstrate your powers by lifting up a car with your hand and putting it back down. “I can do much more than that, but I am also very dangerous, I can’t control it sometimes.” 

“Come with me to Star Labs, we can help.” The Flash holds out his hand, and you take it. He smiles at you and you can’t help but smile back. 


This video has a fun and simple demonstration of the importance of fluid density in buoyancy and stratification. Fresh water (red) and salt water (blue) are released together into a small tank. Being lighter and less dense, the red water settles on top of the blue water, though some internal waves muddy their interface. After the water settles, a gate is placed between them once more and one side is thoroughly mixed to create a third fluid density (purple), which, when released, settles between the red and blue layers. In addition to displaying buoyancy, this demo does a great job of showing the internal waves that can occur within a fluid, especially one of varying density like the ocean. (Video credit: UVic Climate Modeling Group)

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What Einstein demonstrated in physics is equally true of all other aspects of the cosmos: all reality is relative. Each reality is true only within given limits. It is only one possible version of the way things are. There are always multiple versions of reality. To awaken from any single reality is to recognize its relative nature. Meditation is a device to do just that.
—  Ram Dass

Living here on earth, we are so accustomed to gravity’s effects on fluid behaviors that it’s not always obvious how microgravity will affect them. Here astronaut Richard Garriott demonstrates mixing and separating immiscible liquids in space.

Why Physicists Love Super Balls

by Joel N. Shurkin, Inside Science

Super Balls are toys beloved by children because of their extraordinary ability to bounce. Physicists love them for exactly the same reason.

Drop a baseball on the floor and it will hardly bounce at all. Drop a Super Ball from shoulder height, and it will bounce back 92 percent of the way to the drop-off point. Super Balls also are just as bouncy vertically as they are horizontally, and they spin oddly.

“Physicists love it because it has interesting physical properties,” said Rod Cross, retired professor of physics at the University of Sydney in Australia, whose latest paper on Super Balls appears in the American Journal of Physics. His research also demonstrated the odd way all balls roll.

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Physics Dictates...

A long oneshot based off the events of me getting a concussion…Almost completely innaccurate, but still XD For @the-roosevelts :D

Summary: Arthur, the fastest distance runner at school, decides to volunteer for a Physics demonstration. One thing leads to another, and suddenly it becomes very clear he won’t be running for awhile…

Momentum, informally defined, is known as “inertia of motion,” and equals mass times velocity. It’s measured in kilograms times metres per second, or, “kuhgigms,” as Mr Stephens liked to call it.

Arthur wrote his notes down boredly, letting out a small sigh as his writing hand copied the Law in neat cursive; “Law of Conservation of Momentum: The total momentum in a closed, isolated system does not change, therefore the total momentum in a system before a collision is equal to the total momentum in a system after a collision.”

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