# Mass Calculator

This is a basic mass calculator based on density and volume. This calculator takes and generates results of many common units.

### What Is Mass?

The word mass is used to describe how much matter there is in something. (Matter is anything you can touch physically.) We weigh things to figure out how much mass there is. The more matter there is, the more something will weigh. Often, the amount of mass something has is related to its size, but not always. A balloon blown up has less mass than a solid sphere of the same size.

The difference between mass and weight is that weight is determined by how much something is pulled by gravity. If we are comparing two different things to each other, they are pulled the same by gravity and so the one with more mass weighs more.

But imagine the same two objects in space, where the pull of gravity is very small. In space, the objects may have almost no weight. They still have the same volume of matter, though, so it still has mass.

Mass is measured in kilograms, or grams, (but not pounds and ounces ‐ in the U.S., the correct measure of mass is called the "slug."). A 100 kg object has a greater mass than a 5 kg object. An object's mass stays the same wherever it is.

### Weight and Mass

The Moon has less mass than the Earth, so its gravity is less than the Earth's gravity. This means that objects weigh less on the Moon than they do on the Earth.

The Moon's gravity is one sixth of the Earth's gravity. A 70 kg astronaut weighs six times on Earth what he or she would weigh on the moon. But the astronaut's mass is 70kg on the moon and on the earth.

No matter where you are in the universe, the weight of a mass is the force of gravity on the mass. In the metric system force is measured in newtons, hence weight is also measured in newtons. On Earth, a mass of 1 kilogram weighs 9.8 newtons (on Earth, one slug weighs 32.2 pounds).

A better scientific definition of mass is its description as being composed of inertia, which basically is the resistance of an object being accelerated when acted on by an external force. Inertia is seen when a bowling ball is pushed horizontally on a level, smooth surface, and continues in horizontal motion. This is quite distinct from its weight, which is the downwards gravitational force of the bowling ball one must counter when holding it off the floor.

Gravitational "weight" is the force created when a mass is acted upon by a gravitational field and the object is not allowed to free-fall, but is supported or retarded by a mechanical force, such as the surface of a planet. Such a force constitutes weight.

Under Sir Isaac Newton's 300+ year old laws of motion and an important formula that sprang from his work, F =?ma, an object with a mass, m, of one kilogram will accelerate, a, at one meter per second per second (about one-tenth the acceleration due to earth's gravity) when acted upon by a force, F, of one newton.

Engineers and scientists understand the distinctions between mass, force, and weight. Engineers in disciplines involving weight loading (force on a structure due to gravity), such as structural engineering, convert the mass of objects like concrete and automobiles (expressed in kilograms) to a force in newtons to derive the load of the object. Material properties like elastic modulus ‐ the ratio of tensile stress to tensile strain, which determines the resistance to deformity of an object are measured and published in terms of the newton and pascal (a unit of pressure related to the newton).

### What Is Conventional Mass?

The mass of a body is determined by weighing i.e. the comparison of the mass of the object to be weighed with the mass of a standard weight after allowing for necessary correction, particularly their buoyancy correction. Because the weighing instrument indicates a value that is proportional to the gravitational force on the object reduced by the buoyancy of air, the instrument's indication in general, has to be corrected for the buoyancy effect. The value of this correction depends on the density of the object and the density of the air.

Most precision instruments are made of stainless steel, and, to correct for the effect of buoyancy in air of these instruments, a value referred to as conventional mass has been defined. It is used only in precision metrology.