# Einstein’s Mass Energy Relation

**Einstein’s mass energy relation**

Before Einstein, mass and energy were considered as two different physical quantities. But, Einstein from his theory of relativity proved that energy and mass are inter convertible. If ‘m’ mass is destroyed to form energy than mc^{2} amount of energy is obtained. Equivalent mass can be formed by loss of energy too. So mass and energy are inter convertible to each other.

i.e., E = mc^{2 }

Where ‘c’ is the speed of light that is equal to 3×10^{8} ms^{-1}. According to this relation 1 kg of any matter is equivalent to 9×10^{16} J of energy.

Note:Einstein mass energy relation became one of the best theories of the world and a foundation of modern physics along with quantum mechanics. Einstein was awarded with a Noble Prize for his contribution in physics.

**Relativistic Mass:**

The classical idea of mass is that that it is constant quantity. But this is not constant all particles. Macroscopic particle doesn’t hold the concept of constant mass true. We know that energy has inertia associated with it. An object that is moving has more mass than the object in rest, thus it has more mass. This does not mean when we throw gold in the air, its moves and mass gets increases and eventually we turn out rich. But the mass is increased due to the increase of kinetic energy. This increased mass is called relativistic mass. It is calculated by the formula:

$$\text{Relativistic mass}(M_R)= \frac{M_o}{\sqrt{1-\frac{v^2}{c^2}}}$$

where, M_{R} = Relativistic mass in Kg

M_{o} = Stationary/rest mass in Kg

V = Velocity of travelling particle

C = Speed of light

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## 4 Responses to “Einstein’s Mass Energy Relation”

plx sir

How bragg’s law is used to determine the crystal plane spacing ?

Yes plse

How bragg’s law is used to determine the crystal plane spacing ?