1. The problem statement, all variables and given/known data The average lifetime of muons at rest is 2.20 μs. A laboratory measurement on muons traveling in a beam emerging from a particle accelerator yields an average muon lifetime of 14.718 μs. a) What is the speed of the muons in the laboratory? b) What is their kinetic energy? (MeV) c) What is their momentum? (MeV/c) The mass of a muon is 207 times that of an electron. 2. Relevant equations Part A: SQRT(1-(To/T)^2), where To is the average lifetime at rest and T is the second lifetime given in the problem. Part B: KE= M[(1/sqrt(1-B^2))-1] where: M=mass of muon= 105MeV B= v/c, where v (in m/s) is the speed calculated in part A Part C: 3. The attempt at a solution I found Part A, have a question about B, and I don't understand how to calculate C. Part A: SQRT(1-(2.2/14.718)^2)=0.98876c=0.98876(3E8)=2.966E8 m/s Part B equation was given by one of my classmates, but I know I'm doing something wrong. KE=(105 MeV)((1/SQRT(1-((2.966E8)/(3E8))^2)-1)=594.41 MeV I kept getting this one wrong due to user error with those parentheses, but the online homework told me that number was correct, but changed it to 602 MeV?? Is that equation right, and the number accepted was in a range? Is there a way to be more exact in the equation? Part C: p=SQRT(KE*2*m) If the mass of an electron is 9E-31 kg, then a muon is 207 times that, =12439 kg p=SQRT(602*2*12439)=3869, which isn't right. The homework asks for units of MeV/c...does that mean I divide by 3E8? Is that even the correct equation to use? Please help!