Question

An electron with (rest mass $m_0$) moves with a speed of 0.8C. Its mass when it moves with this speed is :

• A. $m_0$
• B. $\frac{m_0}{6}$
• C. $\frac{5m_0}{3}$
• D. $\frac{3m_0}{5}$

Answer 1

The correct option is C $\frac{5m_0}{3}$

According to Einstein's theory of relativity, the change in mass of particle is given as:

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

$=\frac{m_0}{\sqrt{\frac{c^2-(0.8c{)}^2}{c^2}}}$

$=\frac{5m_0}{3}$