Past exam of the mathematics course of the University of Cambridge 2019 ia Paper 4 11A c Solution Created 2026-09-24 Updated 2026-09-29
At time , the accelerated Proton has momentum and, by the relativistic energy-momentum relation, energyThe incident Cosmic microwave background photon adds energy . Since the final state contains only the Delta-plus baryon, conservation of relativistic energy gives its laboratory-frame Lorentz factorIts rest-frame decay time is a proper time, so time dilation gives the laboratory decay time
Past exam of the mathematics course of the University of Cambridge 2020 ia Paper 2 12C b Solution Created 2026-09-24 Updated 2026-09-29
In the parent's rest frame, momentum conservation makes the massive daughter and photon momenta equal and opposite, of magnitude . The relativistic two-body decay formulas giveSince and ,The daughter's Lorentz factor isIf it decays after proper time , time dilation gives , while uniform motion gives . Therefore the event coordinates in the parent frame are
Past exam of the mathematics course of the University of Cambridge 2020 ii Paper 2 37D iii Solution Created 2026-09-24 Updated 2026-09-29
Since ,Relative to the distant observer, the static clock suffers gravitational time dilation. The orbiting clock suffers the same gravitational effect together with the kinematic time dilation caused by its orbital motion, so it accumulates the least proper time.