- #1
Mathmos6
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Homework Statement
A particle with 4-momentum [itex]\textbf{P}[/itex] is detected by an observer with four-velocity U. Show that the speed, v, of the detected particle in the observers rest frame is given by [itex]\sqrt{1-\frac{(\textbf{P}.\textbf{P})c^2}{(\textbf{P}.\textbf{U})^2}}[/itex]
Homework Equations
I have a feeling [itex]E=mc^2=\sqrt{p^2c^2+(m_0c^2)^2}[/itex] will be of use...