Water Cycle

(n.) All the changes of state concerning water from its evaporation, particularly from the oceans, until its return to the oceans. Thus, the amount of water on Earth does not vary.

Watt, James (1736-1819)

Scottish engineer and mechanic. Author of numerous inventions in various fields, he succeeded in particular in creating, in 1767, the first modern steam engine. Nine years later, he designed the double-acting engine. He is credited with Watt's linkage (an assembly of articulated levers), the centrifugal governor, etc.

Watt

(n.m.) Legal unit of power, symbolized by W.

Weight

(n.m.) Force due to the gravity of a celestial body acting on any object possessing mass. It is denoted by P. Its point of application is the center of gravity of the object. Its direction is vertical. Its sense is from top to bottom. The value of the weight P (in N) is equal to the product of the mass (in kg) by the intensity of gravity g (on Earth g = 9.81 N/kg, on the Moon 1.6 N/kg).

Wind Power Plant

(n.) Plant that converts wind energy into electrical energy.

Year

(n.) Duration of the Earth's revolution around the Sun. One year is equal to 365.25 days, or 8,766 hours, or 525,960 minutes, or 31,557,600 seconds.

Zinc

(n.m.) (from German Zink) Atom with atomic number Z equal to 30. It consists of 30 electrons orbiting a nucleus containing 30 protons and 35 or 36 neutrons. Symbolized by Zn. The metal zinc, which has a bluish-white color, melts at 419.5°C. Its boiling point is 906°C. Its density is 7.14 kg/L. It is used in large sheets to cover roofs.