Kilogram

Definition

A kilogram is the base unit of mass in the International System of Units (SI), defined as the mass of a specific physical prototype kept at the International Bureau of Weights and Measures. It serves as a fundamental standard for measuring mass, linking to various scientific, engineering, and everyday applications. The kilogram is crucial in converting and comparing different units of mass and understanding concepts such as weight and density.

5 Must Know Facts For Your Next Test

1. The kilogram was originally defined in 1795 as the mass of one liter of water at its maximum density, which has since changed to be defined by a physical prototype.
2. In 2019, the definition of the kilogram was redefined based on fundamental constants, specifically using the Planck constant, making it more stable and universal.
3. One kilogram is equivalent to approximately 2.20462 pounds, which is often useful for conversions between metric and imperial systems.
4. The symbol for kilogram is 'kg', which is essential for clear communication in scientific writing and calculations.
5. Kilograms are commonly used in various fields such as science, engineering, nutrition, and trade, making it one of the most widely recognized units globally.

Review Questions

• How does the redefinition of the kilogram in 2019 impact scientific measurements and research?
  • The redefinition of the kilogram in 2019 based on the Planck constant enhances the precision and stability of mass measurements. By linking the kilogram to a fundamental constant rather than a physical object, scientists can achieve more consistent results across various laboratories and applications. This change improves reproducibility in scientific research and allows for better international standardization in mass measurement.
• Compare and contrast kilograms with grams and explain how they are related in terms of measurement.
  • Kilograms and grams are both units of mass in the metric system, where one kilogram equals 1,000 grams. The use of grams is more common for smaller masses, such as food items or laboratory samples, while kilograms are preferred for larger masses, such as body weight or bulk materials. This relationship makes conversions between these units straightforward, helping people easily switch between measurements based on context.
• Evaluate the significance of using standardized units like kilograms in global trade and scientific research.
  • Standardized units like kilograms are crucial in global trade because they ensure consistency and clarity when measuring products, reducing errors in transactions and fostering international commerce. In scientific research, having a uniform measurement system allows researchers from different disciplines and regions to collaborate effectively. This uniformity aids in replicating experiments and sharing findings across borders, ultimately advancing knowledge in various fields.

Related terms

Gram: A gram is a metric unit of mass equal to one-thousandth of a kilogram, commonly used for measuring smaller quantities.

Newton:

A Newton is the SI unit of force, defined as the force required to accelerate one kilogram of mass at one meter per second squared.

Mass: Mass is a measure of the amount of matter in an object, typically measured in kilograms, and is a fundamental property that does not change regardless of location.