What is Rest Mass? Explaining Photon Mass Zero

Thread starter imran
Start date Jan 24, 2005
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Mass Photon Photon mass Rest Rest mass Zero

In summary, rest mass is a fundamental property of matter that defines the mass of an object at rest and is also known as invariant mass. It is different from other forms of mass, such as relativistic mass, as it is intrinsic to an object and does not change with its velocity. Rest mass is typically measured in kilograms or electron volts, depending on the field of study. Photons do not have rest mass and this is significant because it allows them to travel at the speed of light, giving them unique properties.

Jan 24, 2005

imran

what is rest mass? why does a photon have rest mass zero? :uhh:

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Jan 24, 2005

Jake

Rest mass is the mass an object has when you are in its frame of refrence (IE its stationary to you). Photons have rest mass zero because they dont have any mass :)

Jan 26, 2005

imran

thank q for ur ans

1. What is rest mass?

Rest mass is a fundamental property of matter and is defined as the mass of an object when it is at rest. It is also known as invariant mass, meaning it does not change with the object's velocity.

2. How is rest mass different from other forms of mass?

Rest mass is different from other forms of mass, such as relativistic mass, in that it is intrinsic to an object and does not change with its velocity. Relativistic mass, on the other hand, changes with an object's velocity and is dependent on the observer's frame of reference.

3. What units are used to measure rest mass?

Rest mass is typically measured in kilograms (kg) or electron volts (eV). In the SI system, the unit for mass is kg, while in the field of particle physics, eV is often used to measure the rest mass of particles.

4. Can photons have rest mass?

No, photons do not have rest mass. They are massless particles and travel at the speed of light. This is supported by the theory of relativity, which states that objects with mass cannot reach the speed of light.

5. What is the significance of a photon having zero rest mass?

The fact that photons have zero rest mass is significant because it allows them to travel at the speed of light. This allows them to have unique properties, such as being able to travel infinitely far without losing energy and having both wave-like and particle-like behavior.