According to Einstein's theory of relativity, as an object approaches the speed of light, its mass appears to increase. This phenomenon is known as relativistic mass or apparent mass. As an object accelerates to higher speeds, its relativistic mass increases, meaning it requires more and more energy to continue accelerating.
The formula for relativistic mass is:
m = m0 / √(1 - v^2/c^2)
Where: m is the relativistic mass, m0 is the rest mass (mass at rest), v is the velocity of the object, and c is the speed of light.
If we consider a body traveling at half the speed of light (v = 0.5c), we can calculate the relativistic mass using the formula. The factor √(1 - v^2/c^2) in the denominator approaches zero as the velocity approaches the speed of light, resulting in a very large relativistic mass.
However, it's important to note that the concept of relativistic mass is not commonly used in modern physics. Instead, the rest mass (m0) is considered as the invariant mass of an object, meaning it remains constant regardless of its velocity. In relativistic equations, such as E = mc^2, the rest mass is used rather than the relativistic mass.
In summary, according to Einstein's theory of relativity, the mass of a body would appear to increase as it approaches the speed of light. However, in modern physics, the rest mass is considered invariant, and relativistic mass is not typically used in calculations and formulations.