Nuclei - Result Question 54
55. An electron with (rest mass $m_0$ ) moves with a speed of $0.8 c$. Its mass when it moves with this speed is
[1991]
(a) $m_0$
(b) $\frac{m_0}{6}$
(c) $\frac{5 m_0}{3}$
(d) $\frac{3 m_0}{5}$
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Answer:
Correct Answer: 55. (c)
Solution:
(c) $m=\frac{m_0}{\sqrt{1-\frac{v^{2}}{c^{2}}}}=\frac{m_0}{\sqrt{\frac{c^{2}-(0.8 c)^{2}}{c^{2}}}}=\frac{5 m_0}{3}$
