Question

What happens to the mass of an electron as its velocity approaches the speed of light?

Answer 1

According to the theory of special relativity, as an object with mass approaches the speed of light, its relativistic mass increases. This phenomenon is described by the relativistic mass-energy equation:

$m=\frac{m_0}{\sqrt{1-\frac{v^2}{c^2}}}$

where:

• $m$ is the relativistic mass of the object,
• $m_0$ is the rest mass (or invariant mass) of the object (which is the mass measured when the object is at rest),
• $v$ is the velocity of the object, and
• $c$ is the speed of light in a vacuum.

As the velocity of an electron increases towards the speed of light, the denominator of the equation becomes smaller, approaching zero. As a result, the relativistic mass of the electron increases without bound. However, it is important to note that the rest mass of the electron, $m_0$, remains constant regardless of its velocity.

It's worth mentioning that the concept of relativistic mass is less commonly used in modern physics, and the focus is often on the rest mass ($m_0$) of particles. In relativistic calculations, it is more convenient to work with other quantities, such as energy and momentum, which are conserved in all reference frames.