## anonymous one year ago In one reference frame, Alex has observed two ﬁrecrackers separated by a distance of 5.00 m exploded at the same time. Meanwhile, Jim has observed one ﬁrecracker exploded 2.25 m ahead of the other. How far from each other are the two ﬁrecrackers in Jim’s reference frame? Anyone wanna help telling me how to do it? Just the flow of how to answer this question :)

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1. IrishBoy123

yes. first, who is flash? is he in a 3rd reference frame? but anyways, start by drawing reference frames for everyone involved in this problem. set one as S, with velocity = 0, then park the others in other frames, S' and S'' if there are 2 others, with velocities relative to S of v' and v'' in this case, if i am reading your question correction correctly, A is moving in the frame of the crackers as he seems them simultaneously explode, whereas Jim sees them as length contracted - and so the chasing cracker should in his frame explode before the leading frame. i would therefore put J as the reference S frame with A moving at speed v' in the S' frame. then we need to figure out who flash is and what he is doing. that needs more informtion from you and might change the best way to do this. PS you can already see that $$\gamma_{A:J} = \frac{5}{2.25}$$ from the length contraction

2. anonymous

ha! I'm sorry :D Flash is Jim :D

3. IrishBoy123

can you scan the question, or link it? that might make life a lot easier :p