**Contents**

*• What is mass?*

*• Where does mass come from?*

*• What are rest mass and relativistic mass?*

*• How to measure mass?*

*• What is weight?*

*• What is the relation between weight and mass?*

*• What is the difference between mass and weight?*

# What is mass?

**inertia**, the most fundamental property of all matter. Where inertia is an inherent property of each body by virtue of which it has a tendency to resist the change in its state of rest or state of motion.

**principle of conservation of mass**, the mass of a body does not change. If a body divided into two or more parts, then the mass also divides with the parts. The sum of the masses of every individual part is equal to the mass of the original one.

**Albert Einstein's**special theory of relativity, the mass of an object is equivalent to energy, the mass and energy can be interchangeable. If the mass of a substance is lost, then the amount of mass lost in the substance is converted into energy.

## Where does mass come from?

**Large Hadron Collider (LHC)**in

**CERN**might now provide a solution for this problem. In this experiment, scientists find a new particle called '

**Higgs boson**' which may provide mass to other particles.

**Higgs field**and the mass comes due to the interaction between particles and the Higgs field. Theoretically, without the Higgs field, there would be no mass of fundamental particles.

**What are rest mass and relativistic mass?**

**special relativity**, the mass has two meanings - one is the

**rest mas**s and another is the

**relativistic mass**. The rest mass of a body is the mass of a body when measured in the reference frame of an observer. Where the relativistic mass of a body, is the mass when the body is observed traveling at a velocity relative to an observer.

**mass-energy equivalence**, rest mass is equivalent to rest energy, while relativistic mass is equivalent to relativistic energy (also called total energy). This relativistic energy of an object was understood to form its rest mass as well as its increase of mass caused by high speed.

**Relation between rest mass and relativistic mass**

**special relativity**, the mass of an object in a frame of reference at rest is called its rest mass m0. When the object comes in motion then a relative change in mass is also perceived, which is the

**relativistic mass**of the object.

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**How to measure mass?**

**kilogram**(the SI unit of mass) and

**gram**(the CGS unit of mass). Where one kilogram is equal to 1000 grams. Actually, one kilogram is a measure of a block of

**Platinum-Iridium alloy**in the shape of a cylinder 39.17 millimeters in both height and diameter.