Question

As you take your leisurely tour through the solar system, you come across a 1.31-kg rock that was ejected from a collision of asteroids. Your spacecraft\'s momentum detector shows a value of 1.71

Answer 1

$p=\gamma mv=m\frac{v}{\sqrt{1-\frac{v^2}{c^2} }}\Rightarrow v=\frac{p}{\sqrt{m^2+\frac{p^2}{c^2}}}=\frac{1.71\cdot 10^8}{\sqrt{1.31^2+\frac{1.71^2}{3^2}}}=1.2\cdot 10^8 m/s$