What is Relativistic Mass?

Relativistic mass is a concept from Albert Einstein’s Special Theory of Relativity. It describes how the apparent mass of an object increases as its velocity approaches the speed of light ($c$). The rest mass ($m_0$) is the mass of the object when it is at rest relative to an observer. As the object gains speed, its kinetic energy contributes to its total mass ($m$).

The formula demonstrates the core principle: as the velocity ($v$) gets closer and closer to $c$, the denominator $\left(\sqrt{1 – \frac{v^2}{c^2}}\right)$ approaches zero. Dividing the rest mass by a number approaching zero causes the relativistic mass ($m$) to increase infinitely. This phenomenon proves that a massive object can never reach the speed of light.

How to Use the Calculator

1. Enter Rest Mass ($m_0$): Input the mass of the object in kilograms (kg) when it is not moving (its inherent mass).
2. Enter Velocity ($v$): Input the speed of the object in meters per second (m/s). You can use scientific notation (e.g., `1.5e8` for $1.5 \times 10^8$).
3. Calculate: Click the “Calculate Relativistic Mass” button.
4. Review Results: The tool will instantly display the step-by-step substitution of your values into the formula and provide the final calculated Relativistic Mass ($m$) in kilograms.