The highest-energy cosmic rays ever detected are protons with energies on the order of 300 EeV.
(a) What’s Earth’s radius as measured in the reference frame of such a proton as it approaches Earth?
(b) Compare the high-energy proton’s total energy with that of a 143-g baseball moving at 100 km/h.
(c) Compare the proton’s momentum with that of the same baseball.