1. The problem statement, all variables and given/known data Q1. Firecrackers are placed at points A and B, which are 100m apart as measured in the rest frame of the earth. As a rocket shop, moving at speed v = 3/5 c, passes point A the firecracker there explodes. As the rocket passes point B, the second firecracker explodes. As read on the rockets clock, the time difference between the explosions was delta te. Clocks synchronized in the rest frame of the earth measure a time interval delta te between the explosions. a) Determine delta te. b) Determince delta te by reasoning using time dilation , and again by reasoning using length contraction. Do your results agree? Should they? Q2. Neutral pions decay into two gamma rays. In its frame of reference, a neutral pion has a lifetime of 8.4 x 10^-17s (it is effectively a clock which ticks once). A particle accelerator produces pions with a speed of 0.99975c. What is the lifetime of the pions measured in the laboratory frame? How far do the pions move in that time? 2. Relevant equations Lorentz transformation for time and length. 3. The attempt at a solution For Q1: a) I do not understand why both measured times are delta te. Is it because the times are measured in their respective frames? Taking delta te to be the proper time in the rest frame of the earth, I calculated delta te = 100/(3/5 c) b) I do not understand what the question is asking. I'm not sure how to approach the question but I think that the results should agree as time dilation should be consistent with the length contraction depending on the frame of reference, am I correct? For Q2: It says in the question "In its frame of reference, a neutral pion has a lifetime of 8.4 x 10^-17s", does this mean that the lifetime given is the proper time since it is in the frame of reference of the pion? From what I understand, for the same event, the time measured in the respective time frame is the same. Its only when one frame is viewed from another that there is a difference in measured time and length. Are these correct? I am still new to this, all help appreciated. Thank you.