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.

Science video from Veritasium! Light is so common that we rarely think about what it really is. But just over two hundred years ago, a groundbreaking experiment answered the question that had occupied physicists for centuries. Is light made up of waves or particles?

Science video from Veritasium! What causes the phases of the moon? The common incorrect answer is the shadow of the Earth. The phases of the moon are actually just a result of our perception of the moon's half-illuminated surface. When the moon does pass through Earth&'s shadow the result is a lunar eclipse. This can be spectacular as the moon turns a deep shade of red. Images courtesy of NASAimages.org and Geoff Wyatt, Senior Astronomy Educator Powerhouse Museum

JJ Thomson proposed the first model of the atom with subatomic structure. He had performed a series of experiments and was credited with the discovery of the first sub-atomic particle, the electron. He therefore proposed a new model of the atom called the plum pudding model. In this model, the plums represent negatively charged electrons which can be plucked out of the atom, leaving behind some positively charged pudding. In this film, cherry tart is used as a delicious substitute for plum pudding.

Science video from Veritasium! 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 weight hits the ground first - the free weight or the weight attached to the chain?

Science video from Veritasium! When a tube spins with an X and an O labelled at either end, why do we see only one letter during the rotation?

Science video from Veritasium looking at the spinning tube trick!

The solution to the question posed in the spinning tube trick video, that is - what would you see if looking at the spinning tube from below a glass table. The explanation of why only the X or O is visible will be the subject of the next video.

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.

An introduction to alpha, beta, and gamma radiation

What forces (i.e. pushes or pulls) are acting on you right now? Most people can identify the gravitational force down, but there must be something else otherwise you would accelerate down towards the center of the Earth. The other main force on you is called the normal force. It is a force perpendicular to the surface that supports you, like the ground or the seat of your chair. You compress this surface and it acts like a spring, pushing you up.

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?)

Science video from Veritasium! A boomerang can execute its unique roundtrip flight by making use of three fundamental physics principles: lift, relative velocity, and gyroscopic precession.

There are a few persistent misconceptions about what causes the seasons. Most believe it is the distance between the Earth and sun which varies to give us seasonal temperature variations. However it is actually the directness of the sun's rays leading to more intense sunshine in summer and less in winter.

If you spin a raw egg and then stop it, it will start spinning again without you having to touch it. A boiled egg, on the other hand, stops and stays stopped. Why is this? Well a raw egg contains a yolk that moves inside the egg independently of the shell. If you stop the shell, the yolk inside continues to move due to its inertia and it therefore gets the egg spinning again.

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.

Science video from Vertiasium! The aurora borealis or northern lights is one of the most spectacular natural displays on the planet. Theories about its origins have been debated for centuries and common misconceptions persist that the aurora is the sun's rays scattered off ice crystals in the high atmosphere. In truth, the light is created more than 100km above Earth&'s surface as high speed electrons and protons ejected from the sun in a solar flare or coronal mass ejection collide with air molecules in the upper atmosphere.

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.

Science video from Veritasium! At the Palais de la Decouverte in Paris, they showed me this experiment where a 1kg aluminium plate is levitated above a large coil of wire that is being supplied with 800A of alternating current at 900Hz. This is by far the best demonstration of electromagnetic induction I have ever seen

Force is a central concept in physics. By analysing the forces on an object, its resulting motion can be determined. But what exactly is a force? The word force is used in everyday language in a variety of contexts, only some of which reflect the scientific definition of force. In this video, people at Victoria Park in Sydney are interviewed on their ideas of force and the forces that act on them.

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.