Comment fonctionne la vis d’Archimède ?
Le concept est simple : on installe une vis d’Archimède sur un cours d’eau, au niveau d’une petite chute. L’eau qui passe dans la vis vient alors la faire tourner sur elle-même. Ce mouvement entraîne une génératrice, ce qui produit de l’électricité. … Ainsi, on peut exploiter des cours d’eau d’un autre type facilement.
Pourquoi spirale logarithmique ?
La spirale logarithmique présente une exceptionnelle stabilité vis à vis des transformations géométriques classiques : – toute rotation de centre O d’angle de la spirale revient à une homothétie de même centre et de rapport , laquelle revient donc à l’identité si .
What is the formula for Archimedes spiral?
- The equation of the spiral of Archimedes is r = aθ, in which a is a constant, r is the length of the radius from the centre, or beginning, of the spiral, and θ is the angular position (amount of rotation) of the radius.
What does spiral of Archimedes mean?
- The Archimedean spiral (also known as the arithmetic spiral) is a spiral named after the 3rd-century BC Greek mathematician Archimedes. It is the locus corresponding to the locations over time of a point moving away from a fixed point with a constant speed along a line that rotates with constant angular velocity.
What is the general equation of a spiral?
- In modern notation the equation of the spiral is r = aeθ cot b, in which r is the radius of each turn of the spiral, a and b are constants that depend on the particular spiral, θ is the angle of rotation as the curve spirals, and e is the base of the natural logarithm.
What is Archimedes Sphere?
- One of the many great mathematical discoveries of Archimedes was the relationship between the surface area of a cylinder and a sphere. Archimedes discovered that a sphere that has the same diameter as the height and width of the cylinder is 2/3 of the surface area of the cylinder.
