inal answer:
The SI base unit of mass is the kilogram (kg), which was historically based on a physical object but has been redefined in 2019 in terms of the Planck constant to maintain its stability over time. A kilogram is about 2.2 pounds, and a gram is 1/1000th of a kilogram.
Step-by-step explanation:
The SI base unit of mass is the kilogram (kg). Historically, it was defined by a platinum-iridium cylinder, known as the International Prototype of the Kilogram (IPK), which was stored at the International Bureau of Weights and Measures near Paris. However, in May 2019, the definition was revised and is now based on fixed numerical values of the Planck constant and other fundamental physical constants. This redefinition ensures that the unit will remain stable over time, unlike the IPK which could lose or gain atoms, and thus mass, over time.
Laboratories commonly use balances for measuring mass, which must be calibrated using a standard mass to ensure accuracy. The kilogram is pivotal in making mass comparisons because all other masses are ultimately compared to it. As of 2019, with the advancement in science and technology, a more accurate way of defining a kilogram using the Kibble balance and Planck's constant has been adopted.
A kilogram is equivalent to about 2.2 pounds, and a gram is exactly 1/1000th (10-3) of a kilogram. These measurements fall under the metric system widely used in scientific and engineering contexts.