Veritasium

Make Plasma With Grapes In The Microwave!

Title: Make Plasma With Grapes In The Microwave!
Runtime: 5:31
Date posted: 15 years ago
Description: When a grape is cut nearly in half and placed in a microwave, plasma is produced. Please use caution if attempting this experiment: don't leave the microwave on for too long, make sure the area is well ventilated, and stand back. Remember the contents will be very hot afterwards.

Title: Slinky Drop
Runtime: 0:57
Date posted: 15 years ago
Description: What happens when a slinky that has been extended under its own weight is released? How does it fall to the ground? Answer link: http://www.youtube.com/watch?v=eCMmmEEyOO0

Title: Slinky Drop Answer
Runtime: 3:31
Date posted: 15 years ago
Description: Want more awesome HD slow-mo? http://www.youtube.com/watch?v=uiyMuHuCFo4
Slinky not long enough? Click here: http://www.youtube.com/watch?v=JsytnJ_pSf8
How does a slinky fall when extended by its own weight and then released? We discover the surprising answer using a slow motion camera that records 300 frames per second. Answer link: http://www.youtube.com/watch?v=oKb2tCtpvNU

For a great explanation, check out Rhett Allain's analysis here: http://www.wired.com/wiredscience/2011/09/modeling-a-falling-slinky/

Title: Slinky Drop Extended
Runtime: 1:58
Date posted: 15 years ago
Description: The answer to the question - what happens to a tennis ball tied to the bottom of a slinky after the top of the slinky is let go?

For a great explanation, check out Rhett Allain's analysis here: http://www.wired.com/wiredscience/2011/09/modeling-a-falling-slinky/

Title: States of Matter
Runtime: 4:53
Date posted: 15 years ago
Description: Everyone is familiar with liquid water, ice and water vapour, but what are the differences between these three states of matter? Solids, liquids and vapours of the same substance differ in the motion of the molecules and the distance between them.

Animations courtesy of VisChem (Trade Mark), Copyright 1995, Roy Tasker. Thanks for all your help!

Title: Imploding Drum
Runtime: 5:01
Date posted: 15 years ago
Description: The atmosphere applies a pressure of about 100 000 N to every square metre on Earth's surface. We take this pressure for granted because we have the same amount of pressure pushing out. But what happens when the pressure of the atmosphere is applied to an object with no outward pressure? It implodes. In spectacular fashion.

Title: What Colour Is Most Attractive?
Runtime: 2:40
Date posted: 15 years ago
Description: Scientific research has shown that heterosexual males and females find members of the opposite sex more attractive when they wear the colour red. This is a subconscious preference that seems to have some evolutionary basis. We attempted to replicate these findings in Sydney but our methods were much less controlled and the results achieved were not statistically significant.

Title: Chain Drop Answer 2
Runtime: 2:42
Date posted: 15 years ago
Description: Which weight hits the ground first - the free weight or the weight attached to the chain?

Title: Chain Drop Experiment
Runtime: 0:38
Date posted: 15 years ago
Description: On a mobile device? Click here: http://www.youtube.com/watch?v=X-QFAB0gEtE for the answer
Two 1.5kg masses are released simultaneously from the top of a 10m high wall. One is attached to a chain while the other is free. Which one will hit the ground first?

Title: Impress Her With Nanodiamonds
Runtime: 1:28
Date posted: 15 years ago
Description: Scientists have recently discovered nanodiamonds in the flames of ordinary candles. They are produced at a rate of about 1.5 million per second. Unfortunately they are also burned up at this rate and released into the atmosphere as carbon dioxide. Still this finding may prove useful in the ongoing search for economical ways to produce diamonds.

Title: What Is Water Made Of?
Runtime: 1:07
Date posted: 15 years ago
Description: It's the most abundant liquid on the planet and by weight we are about 60% water. But do we know what it is made of?

Title: What Is Chemistry?
Runtime: 1:32
Date posted: 15 years ago
Description: 2011 is the international year of Chemistry. But what do Australians know about it?

Title: Ice Cutting Experiment
Runtime: 1:18
Date posted: 15 years ago
Description: On mobile, click here for the answer: http://www.youtube.com/watch?v=qQCVnjGUv24

When ice is put under pressure, its melting point decreases. When that pressure is removed it goes back to being solid. This process is known as 'regelation'. In this experiment regelation of ice is attempted with copper wire and fishing line of the same diameter. Which will pass through the ice first?

Title: Ice Cutting Experiment
Runtime: 2:52
Date posted: 15 years ago
Description: What passes through a block of ice more quickly, copper wire or fishing line?

Title: Does Pressure Melt Ice?
Runtime: 1:38
Date posted: 15 years ago
Description: When pressure is applied to ice, its melting point is reduced so it turns to water. When the pressure is removed, however, it turns back into ice. This process is called 'regelation.' Big thanks to Art of Ice Sculptures www.icesculpture.com.au who donated the beautiful block of ice.

Title: Why Is Ice Slippery?
Runtime: 2:54
Date posted: 15 years ago
Description: In Sydney, ice melts because it is warm out in the middle of the day (even in winter). This creates a layer of water on top that certainly makes it slippery. But should it be slippery at night or in a cold northern climate where the air temperature is below zero? Yes, because the pressure your skates apply to the ice actually lowers its melting point allowing you to glide along a thin layer of water.

Animation in this video is courtesy of VisChem (TM), Copyright 1995, Roy Tasker

For a more complete picture of the mechanisms involved in making ice slippery, check out this great article: http://lptms.u-psud.fr/membres/trizac/Ens/L3FIP/Ice.pdf

Title: How Does The Earth Spin?
Runtime: 4:42
Date posted: 15 years ago
Description: One of the most common physics misconceptions is that an unbalanced force causes constant motion. In truth, an unbalanced force leads to changes in motion - accelerations.

Title: Why Does The Earth Spin?
Runtime: 2:52
Date posted: 15 years ago
Description: The Earth spins on its axis, completing a full revolution every day. By why does it do this? One of the most common misconceptions in physics is the belief that constant motion requires a constant force. So many people believe there must be some force in the Earth (e.g. gravity, centrifugal force) that keeps it spinning. In truth, no force is required because a fundamental property of mass is that it maintains its state of motion in the absence of external forces. This property is called inertia.

Title: Persistence Of Vision
Runtime: 2:49
Date posted: 15 years ago
Description: Everything is not as it first appears. This simple plastic ball looks purple until you swing it in a circle and reveal its true nature. Inside are three light emitting diodes (LEDs), which are red, green and blue. They turn on and off in sequence very quickly. When still, the ball appears purple because your eyes and brain don't 'refresh' quickly enough to perceive the changing colours. However, when swung in a circle, the ball changes colours at different locations so the colours don't merge with each other and the ball's true nature is revealed. Now let's not think too carefully about how this illusion is conveyed through video (because the camera doesn't refresh quickly enough to perceive the colours changing either - so you have no hope of seeing it on YouTube even frame by frame).

Title: Fire Syringe
Runtime: 3:19
Date posted: 15 years ago
Description: When air is compressed very quickly, it can reach high temperatures. In this demonstration we show how cotton wool can reach the point of auto-ignition by quick compression of air in the fire syringe.

Title: Misconceptions About Heat
Runtime: 5:11
Date posted: 15 years ago
Description: When we touch something that is hot or cold, what are we actually sensing? Is it the temperature of the object, or the rate at which heat flows between the object and our hand?

Title: Can You Solve This Shadow Illusion?
Runtime: 3:32
Date posted: 15 years ago
Description: When sunlight shines through a small hole, it casts a circular image on the wall regardless of the shape of the hole. The size of the hole also doesn't affect the size of the image.
This counterintuitive demonstration shows that the hole is acting like a pinhole camera, producing an image of the sun on the wall. Therefore the size and shape of the hole have no effect on the size and shape of the image.

Title: Can You Perceive Acceleration?
Runtime: 3:34
Date posted: 15 years ago
Description: How do our eyes scan across a landscape? Contrary to popular belief, they don't scan smoothly across a scene, they observe a series of images. The eye is capable of panning smoothly however. If something moves in your field of view, your eyes track it smoothly. This has an important effect on our perception of motion. It makes it more difficult to see when objects are accelerating since the eye tracks all motion quite smoothly.

Title: Option E - Acceleration of a Bungy Jump
Runtime: 0:35
Date posted: 15 years ago
Description: On the rebound, the acceleration varies. The jumper is accelerating up but as the bungy recoils, the jumper starts accelerating down again due to the pull of gravity. This does not mean that he's moving down, however, only that his velocity upwards is decreasing.

Title: Option D - Acceleration of a Bungy Jump
Runtime: 1:02
Date posted: 15 years ago
Description: Congratulations, the acceleration of the bungy jump is greatest at the jumper's lowest point. This is because the bungy is now stretched to its maximum, meaning if applies a force up on the jumper more than twice his weight. This means he accelerates up at a greater rate than the acceleration down when he left the platform.

Title: Option C - Acceleration of a Bungy Jump
Runtime: 0:45
Date posted: 15 years ago
Description: At the jumper's fastest point, the acceleration is by definition zero. That is because the jumper is going from speeding up to slowing down. At this instant then there is no change in the jumper's velocity. This is counter-intuitive for a lot of people because it's easy to confuse velocity with acceleration. Velocity is how fast something goes while acceleration is the rate at which velocity changes.

Title: Option B - Acceleration of a Bungy Jump
Runtime: 0:24
Date posted: 15 years ago
Description: When the rope becomes taut, the force on the jumper is mainly his weight downwards, plus a bit of air resistance up. Therefore his speed is increasing nearly as much as it did when he leapt off the platform. So this is not the greatest acceleration of the jump.

Title: Option A - Acceleration of a Bungy Jump
Runtime: 0:32
Date posted: 15 years ago
Description: Right after leaving the platform, the only significant force acting on the bungy jumper is his weight. This causes him to speed up from rest. His speed increases every second by nearly 10 m/s. This is not the maximum acceleration experienced by a bungy jumper, however.

When Is A Bungee Jumper's Acceleration Max?

Title: When Is A Bungee Jumper's Acceleration Max?
Runtime: 1:06
Date posted: 15 years ago
Description: When is the acceleration (rate of speeding up or slowing down) greatest during a bungy jump?

Title: Veritasium Bungee Jumps!
Runtime: 3:10
Date posted: 15 years ago
Description: In Queenstown, New Zealand, I jumped off the Kawarau Bridge - the site of the first bungy jump. It was a thrilling experience, preceded by a terrifying, gut-wrenching half hour wait. All in all an awesome adventure, even if the woman fitting my harness didn't know the first thing about the acceleration of free-falling bodies.

Title: Where Did The Earth Come From?
Runtime: 3:57
Date posted: 15 years ago
Description: Do we take the Earth for granted? It gives us life and sustains us in the manner we're accustomed to, but we don't know the first thing about it: like where did it come from? And how did it form? Most people recognize that the Earth has a big explosion in its history, which they refer to descriptively as the 'Big Bang.' But there are two very good reasons why the Big Bang is not directly responsible for forming the Earth: 1) It happened 13.7 billion years ago. That's more than 9 billion years before the Earth formed (what happened during that time?), and 2) After the Big Bang the universe consisted of only Hydrogen and Helium - not great raw material for building the Earth. The truth is the big bang formed stars, which exploded and then (perhaps) formed more stars, which exploded and then formed our solar system, including the Earth. The early stars performed the vital role of making the heavier elements of which Earth is composed and we are made.

Title: How Old Is The Earth?
Runtime: 2:47
Date posted: 15 years ago
Description: The Earth is clearly old, but exactly how old was difficult to work out. People long believed the Earth had only existed for several thousand years. Then, in the 1800's, a study of geological features (including fjords) led scientists to the conclusion that the planet must be much older - at least millions of years old. Later, the discovery of radioactivity provided a mechanism by which the Earth's core could be continually heated. This meant it was much older than previous estimates of 20-40 million years based on the cooling rate of the Earth. Today through many different methods we have established that the Earth is roughly 4.54 billion years old!

What Is Electricity? (Are You Gonna Be My Girl?)

Title: What Is Electricity? (Are You Gonna Be My Girl?)
Runtime: 3:59
Date posted: 15 years ago
Description: 1, 2, 3 A song about 'lectricity
because it powers our lives
makes it possible for us to thrive

because it powers our lives
makes it possible for us to thrive

Oh, 4, 5, 6, volts of potential difference
makes electrons go round
if the circuit is complete and sound

Circuit's closed
Voltage There
Current Flows
Power Everywhere

We use AC,
in factories
and homes because we can transform it
High voltage
transmits with lower loss
but low voltage is best for safety
I said what is electricity?

Well, so 1,2,3 a song about 'lectricty
because it powers our lives
makes it possible for us to thrive

because it powers our lives
makes it possible for us to thrive

Oh, 4,5,6 volts of potential difference
makes electrons go round if the circuit is complete and sound

Heat makes steam
turns tu...

Title: Types of Radiation
Runtime: 2:55
Date posted: 15 years ago
Description: An introduction to alpha, beta, and gamma radiation

Title: Sound + Fire = Rubens' Tube
Runtime: 4:03
Date posted: 15 years ago
Description: Sound waves in a tube of gas create flames of different heights that dance to the music. A metal tube with holes in it is filled with gas. The gas is lit to create a row of tiny flames. A speaker at one end plays sound into the tube, which creates a standing wave of sound: areas where air molecules are vibrating rapidly separated by areas where the air is fairly still. This produces the different heights of flames and allows the wavelength of the sound wave to be estimated.

Title: Radiation vs Radioactive Atoms
Runtime: 3:01
Date posted: 15 years ago
Description: There seems to be confusion about what radiation is and where it comes from. Many people believe it is the radiation that comes directly from nuclear power plants that poses a threat to public safety. In fact it is the radioactive atoms, which can escape in the event of an explosion, that pose a safety risk. They can be scattered by the wind over hundreds of kilometres. Then they may be ingested or breathed in. If they release radiation at this point, it is damaging to the body's molecules and cells because the radiation is delivered directly to tissues.

Title: Galileo the Scientific Parrot
Runtime: 2:36
Date posted: 15 years ago
Description: On the surface of Earth all objects accelerate downwards at the same rate - at least, they're supposed to. But we all know dust, pieces of paper, and feathers fall slower. This is of course due to the influence of air resistance. In this experiment we use an evacuated cylinder to test whether a coin and feather really do accelerate at the same rate.

Title: What Powers Australia?
Runtime: 3:18
Date posted: 15 years ago
Description: Countries are powered by a diverse range of energy sources, but in Australia electricity generation mainly has one source: fossil fuels. Coal, natural gas, and oil account for over 90% of the country's electricity. Hydro provides 7% with only 0.3% provided by wind and solar. Should Australia consider nuclear power? It is a complicated issue leaving many uncertain about its place in Australia's energy future.

Title: How Damaging is Radiation?
Runtime: 3:59
Date posted: 15 years ago
Description: What is radiation? Are all types harmful? What are the most common sources of damaging radiation? Most people view radiation as harmful and negative without understanding what makes it potentially damaging and which forms should be avoided. For example, many felt radiation from mobile phones probably caused cancer but few focused on the carcinogenic effects of UV rays.

Title: Supercooled Water - Explained!
Runtime: 3:36
Date posted: 15 years ago
Description: Many videos on YouTube show water freezing almost instantaneously. This video shows you how to replicate the experiment and it explains how the phenomenon works. Molecular illustrations are courtesy of:
PhET Interactive Simulations
University of Colorado
http://phet.colorado.edu.

Title: What Are Atoms and Isotopes?
Runtime: 2:58
Date posted: 15 years ago
Description: Most people recognize that atoms are the fundamental building blocks of all matter around us. An atom itself is composed of protons, neutrons and electrons. The simplest atom is the hydrogen atom because it consists of only one proton and one electron. If a neutron is added to the nucleus, the atom is still hydrogen, just a more massive version. Atoms of the same element (i.e. those with the same number of protons) but different numbers of neutrons are called isotopes.

Khan Academy and the Effectiveness of Science Videos

Title: Khan Academy and the Effectiveness of Science Videos
Runtime: 8:04
Date posted: 16 years ago
Description: My PhD: https://ve42.co/phd
It is a common view that "if only someone could break this down and explain it clearly enough, more students would understand." Khan Academy is a great example of this approach with its clear, concise videos on science. However it is debatable whether they really work. Research has shown that these types of videos may be positively received by students. They feel like they are learning and become more confident in their answers, but tests reveal they haven't learned anything. The apparent reason for the discrepancy is misconceptions. Students have existing ideas about scientific phenomena before viewing a video. If the video presents scientific concepts in a clear, well illustrated way, students believe they are learning but they do not engage with the media on a deep enough level to realize that what was is presented differs from their prior knowledge. There is hope, however. Presenting students' common misconceptions in a video alongside the scientif...

Title: Experiments A Cappella
Runtime: 1:06
Date posted: 16 years ago
Description: A short a cappella tribute to experimentalists. It is sung while performing three simple experiments with household items: Mentos dropped in diet Coke, a tea bag emptied and burned, and a ping pong ball floating in the air stream of a hair dryer.

Title: Three Incorrect Laws of Motion
Runtime: 2:29
Date posted: 16 years ago
Description: Newton's Three Laws of Motion are a landmark achievement in physics. They describe how all objects move. Unfortunately most people do not really understand Newton's Laws because they have pre-existing ideas about the way the world works. This film is about those pre-existing ideas. By recognizing what people are thinking, it becomes easier to describe the correct scientific concepts of Newton's Three Laws and how they differ from this 'intuitive physics'.

Title: Is There Gravity In Space?
Runtime: 2:22
Date posted: 16 years ago
Description: If you've seen footage from the International Space Station or any of the space shuttle missions, you know that astronauts float around as they orbit the Earth. Why is that? Is it because the gravitational force on them is zero in space? (Or nearly zero?) The truth is that the strength of the gravitational attraction is only slightly less than it is on Earth's surface. So how are they able to float? Well, they aren't floating - they're falling, along with the space station. They don't crash into the Earth because they have a huge orbital velocity. So as they accelerate towards the Earth, the Earth curves away beneath them and they never get any closer. Since the astronauts have the same acceleration as the space station, they feel weightless. It's like being in a free-falling elevator (without the disastrous landing).

Director of Photography: Stefan Smith
Camera Assistant: Raa Perajeev
Boom Operator: Maha Sivalingam

Production Coordinator: Adrian T...

Title: Misconceptions About Falling Objects
Runtime: 3:22
Date posted: 16 years ago
Description: If you drop a heavy object and a light object simultaneously, which one will reach the ground first? A lot of people will say the heavy object, but what about those who know both will land at the same time? What do they think? Some believe both objects have the same gravitational pull on them and/or both fall to the ground with the same constant speed. Neither of these things is true, however. The force is greater on the heavy object and both objects accelerate at the same rate as they approach the earth, i.e. they both speed up but at the same rate.

Title: Which Hits The Ground First?
Runtime: 3:03
Date posted: 16 years ago
Description: A basketball and a 5kg medicine ball are dropped simultaneously. Which one hits the ground first? It seems obvious that the heavy one should accelerate at a greater rate and therefore land first because the force pulling it down is greater. But this is forgetting inertia - the tendency of mass to resist changes in motion. Therefore, although the force on the medicine ball is greater, it takes this larger force to accelerate the ball at the same rate as the basketball.

Title: Calculating Gravitational Attraction
Runtime: 3:31
Date posted: 16 years ago
Description: Newton's Law of Universal Gravitation can be summarized as "all mass attracts all other mass." But if this is true, why don't we notice the gravitational force of attraction between everyday objects? The reason is because the gravitational force is quite weak.

Title: Best Film on Newton's Third Law. Ever.
Runtime: 4:38
Date posted: 16 years ago
Description: There is a gravitational force of attraction between the Earth and the moon, but is it mutual? That is, are the forces on the Earth and the moon equal? Most people would say no, the Earth exerts a greater force of attraction because it is larger and has more mass. This is a situation in which Newton's Third Law is relevant. Newton's Third Law says that for every force, there is an equal and opposite reaction force. So the force the Earth exerts on the moon must be exactly equal and opposite the force the moon exerts on the Earth. But how can that be - that the same size force keeps the moon orbiting, but barely affects the Earth? The answer is inertia - the tendency for all objects with mass to maintain their state of motion. Since the Earth has much more mass than the moon, it has greater inertia and therefore experiences much less acceleration for the same amount of force.

Title: What Is Gravity?
Runtime: 2:08
Date posted: 16 years ago
Description: People have a lot of different ideas about what gravity is: a downward force that stops you from flying off into space, an attraction smaller objects experience towards larger objects, or a mutual attraction between all masses. It is the last of these ideas that best reflects a scientific conception of gravity.

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FEATURED CHANNELS

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US CITIES

AFRICA

ASIA PACIFIC

AUSTRALIA+

EUROPE

INDIA

LATIN AMERICA

MIDDLE EAST

RUSSIA+

UNITED KINGDOM

The News Access Store

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Subscribe via Email

Credits