Mass is everywhere! The keyboard you’re typing on, the screen you’re reading off of – all these things have mass!

When a number of experimental mass measurements are averaged, the error (the difference between the measured mass and the true mass) will vary inversely with the number of measurements, n.

## Units of Mass

There are several standard units used in measuring mass: gram, kilogram, and tonne. The kilogram is the base unit of mass in the SI system of measurement. It is equal to 2.2046262 pounds.

A kilogram is a solid, cylindrical artifact made of platinum and iridium alloy that is kept in a vault in France along with six official copies. The International Prototype Kilogram, or IPK, is the standard to which other kilogram weights are measured.

It is important for students to understand the difference between mass and weight. While both are measurements of the quantity of matter that an object contains, mass is independent of location, whereas weight depends on gravity. In physics, mass is the quantitative measure of inertia, an object’s resistance to change in velocity or position when some force acts on it. Weight is the downward force produced by the acceleration due to gravity. In order to overcome this influence, a balance scale is used to measure the upward and downward forces on an object to find its mass.

## Units of Weight

Often, people use the words “weight” and “mass” interchangeably. However, these are different quantities, with weight relating to gravity and mass referring to the matter in an object.

A common method of measuring “weight” is to use a spring scale or balance scale. This type of scale measures the force on an object by comparing it to reference objects that have known masses. This method of measurement can only be performed on Earth since it depends on the gravitational field of the planet.

While the SI unit of mass is kilograms (kg), many people and some textbooks still talk about weight in terms of pounds or pound-mass. The official metric unit of force is the newton, but some non-SI units such as kilogram-force and dyne are also used. The avoirdupois pound is an international standard unit of weight, and it can be written with the symbol lb or lbf to avoid confusion with the metric unit of force.

## Units of Force

Using Newton’s second law of motion, the force on an object is directly proportional to its mass and inversely proportional to its acceleration. Therefore, the unit used to describe an object’s force must be consistent with its measurement of mass.

The SI unit of force is the newton, abbreviated N. One newton is defined as the force that causes a mass of 1 kilogram to accelerate at 1 meter per second squared. Other non-SI units of force include the gram force, pound force and sthene.

The gram force, which is in the CGS system of units, is equal to 1/1000 of a newton. The pound force, which is in the English system of units, is equal to 0.1382 newtons. The sthene, which is in the metric system of units, is equal to 1/1000 kilonewtons. These units are rarely used in scientific measurements. However, they are used to measure large objects, such as trains, trucks and bridges.

## Units of Density

Density, which is the mass of a material per unit volume, is an essential measurement in several sciences. It helps scientists determine how a substance will behave under certain conditions such as whether it will float or sink in water, and is also used to identify substances. In the International System of Units, density has the units of grams per cubic centimeter (g/cm3) and kilograms per cubic meter (kg/m3). In the United States, density is often listed in units such as g/mL or kg/L.

In addition to its fundamental role in identifying different substances, density is a key property of materials and has important applications in a variety of fields such as chemistry and the study of mineralogy. It’s also crucial to understanding atmospheric phenomena such as weather patterns and airplane performance, since the density of air changes at different altitudes. Density has derived units, such as kilograms per cubic meter and g/cm3, which make it easy to confuse with other common base units.