Hydraulics

Hydraulics, as commonly understood and applied, is the science deeling with the action and use of the water. Water is the most common luguid. Water is the chemically pure state is not found in nature. Inland waters, which contain varying quantities of salt and mineral matter in solution, occur chiefly as streams, lakes, springs and underground supplies.

Hydraulics units. In all English - speaking countries, the three primary units are the foot, the pound and the second.

There are two important types of hydraulics units: unit of volume and a unit of flow. The most important unit of volume is the cubic foot, in the United States, the gallon /0,13 cu Ft/. The cubic foot per minute is the standard unit of flow, in the United States - the gallon per minute.

Properties of water. A fluid is a substance, which offers very little resistance to change of form and readily takes the shape a solid body – with which it comes in contact.

Compressibility. Though in common water is assumed to be incompressible, it is, like other liquids, slightly compressible. It is also perfectly elastic.

Viscosity. The ability of water to resist movement between its particles is termed viscosity.

It may be described as thick ness.

Adhesion and cohesion cause water to rise above the outside level.

Vocabulary:

flow - течение, поток

fluid - жидкость

compressibility - сжимаемость

viscosity - вязкость

cubic foot - куб. фут. ⁼ 38317,016 см³

gallon - галлон = 4,5459631 дм³.

Adhesion-трение

Cohesion-сцепление

a) Give the definition of hydraulics and viscosity.

2. Ответьте на вопросы.

1. In what state is water found in nature?

2. What hydraulic units do you know?

3. What properties of water do you know?