Physics Demo Videos: Fluids and Matter

Physics Demo Videos: Fluids

Videos of demonstrations illustrating concepts related to fluids, density, pressure, Archimedes’ Principle, Pascal’s Principle, and Bernoulli’s Principle.

For other videos from our demonstration collection, please visit Physics Demo Videos. You may also wish to view our Video Lecture Series for short tutorials on topics from first year physics.

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Bed of Nails. When the pressure is distributed over many nails, each individual nail exerts too small an amount to pop the balloon. When a less dense population of nails is used, each individual nail exerts more pressure and the balloon pops.Balloon pressed down into a bed of nails
Bed of Nails 2: the agony of the feet. When the force is distributed over many nails, each individual nail exerts too small an amount to puncture the foot. Do not try this with only three nails!Person standing barefoot on a bed of nails
Cartesian Diver. The diver-shaped glass in the cylinder has a small hole in the bottom. When pressure is applied to the rubber membrane covering the cylinder, more water is forced into the diver, causing an change in its average density. When this density is less than water, the diver will float; when it is more the diver sinks. Done carefully, an equilibrium point can be found where the diver is suspended in the water.Cartesian diver apparatus
Crush soda can. A small amount of water is heated in a soda can until steaming. The can is then quickly put in cool water, mouth side down. The sudden change in temp causes the steam to condense, resulting in a significant drop in pressure, making the pressure inside much less than atmospheric pressure. Thus, the can collapses under the pressure.Open, empty soda can placed upside down in tray of water
Magdeburg Hemispheres. Two hemispheres are placed together and evacuated. Pulling even these small hemispheres apart is hard!Two people trying to pull the evacuated Magdeburg hemispheres apart
Magdeburg Suction Cups. Two suction cups are placed together and compressed to force out all the air. The vacuum seal created when you pull on the suction cups.Two people pulling on suction cups pressed together
Marshmallow Man. The air pockets in jet-puffed marshmallows will expand in a vacuum. This makes the marshmallow man get bigger as the pressure inside the bell jar gets lower.A little man made out of marshmallows in a vacuum chamber
Shaving Cream in Vacuum. The air pockets in shaving cream will expand in a vacuum. This makes the cream get bigger as the pressure inside the bell jar gets lower.Shaving cream in evacuated bell jar
Which Will Float, Regular or Diet? Sugar is a lot more dense than artificial sweeteners. Thus, a regular soda is more dense than a diet soda. When placed in water, the regular soda, being more dense than water, will sink. The diet, being less dense than water, will float.Two cans of soda in a water-filled aquarium
Inverted Liquid. An index card is placed on top cylinder full of water. The cylinder is then inverted. A slight vacuum is created, keeping the index card sealed to the cylinder, thus keeping the water from pouring out.A completely filled cylinder of water

Archimedes’ Principle

Hollow Globe in Vacuum. When in the atmosphere, the globe experiences a buoyancy force upward exerted by air. When the air is removed, the buoyancy force is also removed and it is clear that the globe weighs more than the cylinder.Balance with hollow sphere on one side and a mass on the other

Pascal’s Principle

Pascal’s Vases. Water pressure is dependent on depth only. Thus, two differently shaped vases will show the same pressure at the same depth.Pascal's vases: two cans partly  filled with water, bottoms connected by hose

Bernoulli’s Principle

Bernoulli Envelope. Blowing air over the open end of an envelope causes the two sides to separate due to the lower pressure of the air flowing along the outside of the envelope.
Person blows on an envelope whose end is slit
Flettner Rotor. A moving, spinning spool will curve due to the addition or subtraction of pressure effects. The side that is spinning in the direction of the motion will have a higher pressure than the side spinning away, thus the spool will curve to the low pressure side.Person shoots spool with wrapped rubber band
Floating Ping Pong Ball. A ping pong ball can be “floated” on a stream of air. The air rushing around the ball creates a pressure low enough to lift and support the ball. The air moves fastest in the center of the stream, so the ball stays centered, even with the nozzle tilted.Ping pong ball floats in a stream of air
Air Over Paper. A stream of air over paper creates a low pressure zone which lifts the paper.Person blows across top of a piece of paper
Ping Pong Ball w/Funnel. When a ping pong ball is placed in a funnel with the air blowing out, the ball won’t fall out of the funnel. The rushing air creates an area of low pressure that holds the ball in place.A ping pong ball held in a funnel
Boomerang (outside). A boomerang will lift and curve when thrown.Boomerang toss
Boomerang (inside). A boomerang will lift and curve when thrown.Nerf boomerang toss
Curve Ball. A moving, spinning ball will curve due to the differing pressures on opposite sides of the ball. The side that is spinning in the direction of the motion will have a higher pressure than the side spinning away, thus the ball will curve to the low pressure side.Curve ball
Siphon. An initial vacuum (provided by sucking) is enough to begin a flow of liquid from the high beaker to the low one.
Siphoning water from one beaker to another
Venturi Tubes. Air flowing through a narrow pipe created a lower pressure than air flowing through a wider pipe.Venturi tubes: the fluid rises higher beneath the narrower section of tube