Carbonate ion (CO₃²⁻)

A compound ion produced from carbonic acid by releasing protons.

The battle of Megiddo

Pharaoh Thutmose III defeated the rebellious coalition of Canaanite vassal states led by the king of Kadesh.

Alesia (France, 1st century BC)

The Gaul city Alesia, defended by Vercingetorix, was besieged by the Roman forces of Julius Caesar in 52 BC.

Solids of revolution (rectangle)

Rotating a rectangle around its axes of symmetry or around its sides results in solids of revolution.

Simple harmonic motion and uniform circular motion

Simple harmonic motion can be considered to be the one-dimensional projection of uniform circular motion.

Tiktaalik

A transitional form between fish and tetrapods, or four-limbed vertebrates.

Woodwind instrument

Woodwind instruments differ from brass instruments mainly in their reed.

Gold mining (19th century)

The California Gold Rush started in 1848, near San Francisco.

European colonisation of the Americas (up to 1763)

Several European countries joined the conquest of the New World, making America a colourful continent.

Opera House (Sydney, 1973)

Due to its design and location, the Opera House of the Australian city is one of the most extraordinary opera houses in the world.

Suction pumps and direct action pumps

Direct action pumps and suction pumps are among the simplest water pumps.

Photosynthesis (basic)

Plants are capable of converting inorganic substances (carbon dioxide and water) into organic sugar.

Dóm Square (Szeged, Hungary)

The Votive Church of Szeged, located on the Great Plains of Hungary, emerges from the buildings of the city's famous square, while the National Pantheon can...

The battle of Actium (31 BC)

In the battle fought at the shores of Hellas, Octavian won a decisive victory over Marcus Antonius.

Battle of Hastings (1066)

The battle ended with the victory of William the Conqueror´s Norman army over the English.

Surface area of spheres (demonstration)

The surface of a sphere consists of the set of points which are all at the same distance from a given point in space.

Volume of spheres (Cavalieri´s principle)

Calculating the volume of a sphere is possible using an appropriate cylinder and cone.

Peptide bond

Amino acids that make up proteins are bound by peptide bonds.

Mexican redknee tarantula

One of the best known species of spiders, often kept as pets. Its bite is not fatal for humans.

Flat feet

Flat feet, or fallen arches, may cause a number of health problems.

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