Windmills stay put. The tower does not move.
The blades rotate when wind blows. Most modern wind turbines are made to start producing electrical energy when the wind blows at 3 or 4 meters per second, they achieve maximum (rated) power production in winds around 8 meters per second and shut down when the winds reach 25 meters per second. The 50 meter long (100 m diameter) blades of a 2 MW turbine rotate at about 14 rpm when the wind is 8 m/s; the tips of the blades are then moving at about 75 m/s.
it is the square blade
The average size of a windmill blade ranges from 35 to 45 meters (115 to 148 feet) in length.
It's called "blade" or a "sail".
vane - Any of several usually relatively thin, rigid, flat, or sometimes curved surfaces radially mounted along an axis, as a blade in a turbine or a sail on a windmill, that is turned by or used to turn a fluid.
Windmill sails Vane - Any of several usually relatively thin, rigid, flat, or sometimes curved surfaces radially mounted along an axis, as a blade in a turbine or a sail on a windmill, that is turned by or used to turn a fluid.
vane
J.S Risdon inventeed it and in December 1872
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Technically, it is. Each blade is a lever, with the axle being the fulcrum of each lever.
Its very, very tall. The largest windmill in the world (currently) is the Enercon E-126. It's blades are just over 200 feet long and the windmill height including the blade at vertical position is around 650 feet (taller than two football fields)!
The average cost of windmill blades for a typical wind turbine installation is around 30,000 to 50,000 per blade.
Yes, a windmill typically has rotational symmetry because it looks the same when rotated around its central axis by certain angles. This is commonly seen in the blades of a windmill where each blade is identical and symmetrically arranged around the axis.