Answer:
v = 0.6c = 1.8 x 10⁸ m/s
Explanation:
From Einstein's theory of relativity, we know that the length of an object contracts while traveling at a speed relative to speed of light. The contraction is according to following equation:
[tex]L = L_{0}\sqrt{1 - \frac{v^2}{c^2}}[/tex]
where,
L = Relative Length
L₀ = Rest Length
According to given:
L = 0.8 L₀
c = speed of light = 3 x 10⁸ m/s
v = relative speed of train = ?
Therefore,
[tex]0.8L_{0} = L_{0}\sqrt{1 - \frac{v^2}{c^2} } \\\\0.8 = \sqrt{1 - \frac{v^2}{c^2} }[/tex]
squaring on both sides:
[tex]0.64 = 1-\frac{v^2}{c^2}\\\\\frac{v^2}{c^2} = 1-0.64 \\v^2= 0.36c^2\\[/tex]
taking square root on both sides:
v = 0.6c = 1.8 x 10⁸ m/s
