质量基础

质量是物理体中物质数量的测量。与重量（物体上的重力）不同，质量无论位置如何都保持恒定。它是物质的基本属性。

介绍

Mass is one of the fundamental properties of matter, representing the amount of substance in an object. It is intrinsic to the object and remains constant regardless of location, unlike weight which varies with gravitational field strength.

历史

The concept of mass evolved from ancient balance scales to Newton's laws of motion. The kilogram was originally defined in 1795 as the mass of one liter of water. In 2019, it was redefined using Planck's constant, making it based on fundamental physical constants rather than a physical artifact.

关键单位

Kilogram (kg)

The SI base unit of mass, defined by Planck's constant since 2019.

Gram (g)

Equal to 0.001 kg, commonly used for small objects and cooking ingredients.

Pound (lb)

An imperial unit equal to approximately 0.453 kg, still widely used in the United States.

Ounce (oz)

Equal to 1/16 of a pound or approximately 28.35 grams.

Ton (metric)

Equal to 1,000 kg, used for large masses like vehicles and cargo.

应用

  • Cooking and baking recipe measurements
  • Medical dosing and pharmaceutical calculations
  • Shipping and logistics weight limits
  • Scientific research and laboratory work
  • Manufacturing quality control and specifications
  • Fitness and health monitoring

Mass-Energy Equivalence

E = mc²

Einstein's famous equation showing the equivalence of mass (m) and energy (E), where c is the speed of light.