According to relativity theory a particle of mass m with a momentum of 2mc has a speed of:
A) 2c
B) 4c
C) c
D) c/2
E) 0.89c

Question

Quizplus · Accepted Answer

According to the theory of relativity, the momentum $p$ of a particle is given by the equation $p = \frac{mv}{\sqrt{1 - \frac{v^2}{c^2}}}$, where $m$ is the rest mass of the particle, $v$ is its velocity, and $c$ is the speed of light. Solving this equation for $v$ when $p = 2mc$ leads to a velocity $v$ that is less than $c$, specifically around $0.89c$. This is because as the velocity of an object approaches the speed of light, its mass effectively increases, requiring exponentially more energy to further accelerate, thus preventing any object with mass from reaching or exceeding the speed of light.

According to Relativity Theory a Particle of Mass M with a Momentum