Calculate Relativistic Mass Growth

Calculator for the mass which a body gains with speed. This mass growth only becomes perceivable at percentages of the speed of light. Although the relativistic mass growth occurs at every speed, at those low speeds common in our surroundings, it hardly matters. Therefore, as unit for mass growth nanograms is preselected, which is a billionth of a gram. If the speed approaches to the speed of light, a larger unit should be selected. The speed must be smaller than the speed of light. Enter rest mass and speed and change the speed of light if you want to calculate for a certain medium. Resulting mass and mass growth will be calculated.

The formula is m = m₀ / √ 1 - (v²/c²) and Δm = m - m₀.

Examples: an 80 tons heavy plane, flying with 1200 kilometers per hour, gains about 50 μg (micrograms), or one twenty thousandths of a gram. A hypothetical spaceship, flying with 86.6 percent of the speed of light, almost doubles its mass.

Relativistic mass growth is the reason why bodies or particles with rest mass can only move at speeds below the speed of light. The growth in mass increases the closer the object approaches the speed of light. Upon reaching the speed of light, the mass would ultimately be infinite, which is of course impossible.
At 10 percent of the speed of light, the increase in mass is about 5 per mille, at 50 percent of the speed of light, the mass increases by about 15.5 percent, and at 99 percent of the speed of light, the mass increases more than sevenfold. Acceleration in these ranges therefore requires increasingly more energy for smaller gains in speed.
Particles without rest mass, such as photons, move at the speed of light and have momentum and energy. If they were to slow down below the speed of light, these energy and momentum would be zero.

Rest mass m₀:
Speed of light c:		m/s
Speed v:
Mass at speed m:
Mass growth Δm: