Kilogram

Definition

A kilogram is the base unit of mass in the International System of Units (SI), defined as being equal to the mass of a specific physical object known as the International Prototype of the Kilogram. It is a fundamental measurement used globally for quantifying weight and mass, forming the basis for other units in the metric system, such as grams and metric tons.

5 Must Know Facts For Your Next Test

1. The kilogram was originally defined by a physical object made of platinum-iridium that was kept at the International Bureau of Weights and Measures until 2019, when it was redefined based on fundamental constants.
2. The symbol for kilogram is 'kg', and it is one of the few SI base units with a prefix (kilo) included in its name.
3. Kilograms are widely used in scientific research, industry, and everyday life for measuring mass, weight, and even food quantities.
4. In many countries, including those that use the Imperial system, the kilogram is often used alongside pounds for weight measurement due to its global acceptance.
5. The kilogram's importance in commerce, trade, and science makes it an essential unit in calculating dimensions, material properties, and food portions.

Review Questions

• How does the kilogram function within the metric system and why is it considered a base unit?
  • The kilogram serves as the base unit of mass in the metric system, providing a standard measurement from which all other mass units are derived. Its definition as equal to the mass of a specific prototype makes it foundational for scientific calculations and everyday measurements. Other units like grams and metric tons are directly related to kilograms through simple multiplication or division, highlighting its central role.
• Discuss how the redefinition of the kilogram in 2019 has impacted scientific measurements.
  • The redefinition of the kilogram in 2019 shifted from being based on a physical object to being determined by fundamental constants, specifically the Planck constant. This change has made measurements more precise and consistent over time, as it no longer relies on a single artifact that could potentially change in weight. This advancement aligns with modern technology, ensuring that scientific measurements remain accurate globally.
• Evaluate the significance of using kilograms in both everyday life and scientific research, particularly in terms of global standardization.
  • The widespread use of kilograms in everyday life and scientific research emphasizes its role in global standardization. In daily activities like cooking or purchasing goods, kilograms allow for clear communication about quantities across different regions. In science, using a standardized unit like the kilogram enhances collaboration among researchers worldwide, facilitating shared understanding and accuracy in experiments. This uniformity contributes to effective trade practices and promotes consistency across various fields.

Related terms

Gram: A gram is one-thousandth of a kilogram and is commonly used for measuring lighter objects, especially in cooking and nutrition.

Metric Ton: A metric ton is equivalent to 1,000 kilograms and is used for measuring large quantities, often in contexts such as shipping and industry.

Newton:

A Newton is a unit of force that can be derived from mass; one Newton is the force required to accelerate one kilogram of mass by one meter per second squared.