The question provides momentum that the muons move with (3094 MeV/c) and proper lifetime (2.198 micro seconds) and asks to find the dilated lifetime. 2. t= to/((1-u^2/c^2)^1/2) and p=(mv)/((1-v^2/c^2)^1/2) 3. I think that I am supposed to use the momentum given to back order velocity then use that with the time dilation equation but I'm not sure what units I should use for the mass of the muon. I saw one with kg and one with MeV/c and I feel like I should use MeV/c but I'm not getting the units to work out and I'm just going no where right now. Any help would be nice. Thanks.