Question

When a material particle of rest mass ${}^{\prime }{m}_0^{\prime }$ attains the velocity of light, its mass becomes.

• A. $0$
• B. $2m_0$
• C. $4m_0$
• D. Infinity

Answer 1

The correct option is D Infinity

Rest mass of an object is the inertial mass of that object when it is at rest. The relation between object's mass and rest mass is given by:

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

where $m_0$ is rest mass, $v$ is velocity of object and $c$ is speed of light.
Now, if some particle attains the velocity of light then according to the equation mentioned above it's mass becomes infinity.