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Bar

Definitions and Applications

  1. Unit of Pressure
    • Definition: A bar is a metric unit of pressure, not part of the International System of Units (SI), but accepted for use with SI. One bar is defined as exactly 100,000 pascals (Pa), which is equivalent to 100 kilopascals (kPa).
    • Conversions:
      • 1 bar = 100,000 Pa
      • 1 bar ≈ 750.07 mmHg (millimeters of mercury) at 0°C and latitude 45°
      • 1 bar ≈ 14.5 psi (pounds per square inch)
    • Applications:
      • Meteorology: Atmospheric pressure is often measured in millibars (mbar), where 1 bar = 1,000 mbar.
      • Engineering: Used to specify pressure in various systems, such as tire pressure, hydraulic systems, and scuba diving tanks.
  2. Rod
    • Definition: A straight, solid piece of material, typically cylindrical or rectangular in cross-section.
    • Applications:
      • Construction: Used as structural elements in buildings, bridges, and other infrastructure.
      • Machinery: Used in the construction of mechanical parts, such as connecting rods in engines.
  3. Railway Pivoted Bar
    • Definition: A pivoted bar, often parallel to a running rail, used in railway systems.
    • Functions:
      • Holding Points: Ensures the correct alignment of the rails for the safe passage of trains.
      • Train Detection: Provides information about the position of a train by being depressed by the train wheels.
    • Applications:
      • Railway Safety: Integral part of railway signaling and safety systems to prevent accidents and ensure smooth operation.
  4. Material of Uniform Cross-Section
    • Definition: A piece of material that has the same cross-sectional shape along its entire length. This material can be produced by casting, rolling, or extruding.
    • Types:
      • Cast Bar: Formed by pouring molten material into a mold where it solidifies.
      • Rolled Bar: Created by passing the material through rollers to achieve the desired shape and size.
      • Extruded Bar: Produced by forcing the material through a die to achieve the desired cross-section.
    • Applications:
      • Manufacturing: Used in the production of components for various industries, including automotive, aerospace, and construction.
      • Metalworking: Basis for further processing into parts, tools, and machinery.

Summary

A bar can refer to a unit of pressure, a rod, a pivoted bar in railway systems, or a material with a uniform cross-section. Each definition has distinct applications, ranging from measuring atmospheric pressure to forming structural components in construction and engineering. The versatility of the term “bar” reflects its broad usage across different fields and industries.

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