# LOG#052. Chewbacca’s exam.

I found this fun (Spanish) exam about Special Relativity at a Spanish website: Solutions:

1) 2) 3) t=13.6 months = 13 months and 18 days.

Calculations:

1) We use the relativistic addition of velocities rule. That is, where u=Millenium Falcon velocity, v=imperial cruiser velocity= c/5, y V=relative speed=4c/5.

Using units with c=1:

4/5=(v-1/5)/(1-v/5)

4/5(1-v/5)=v-1/5

4/5-4/25v=v-1/5

29/25 v=1

v=25/29

Then, reinserting units.

2) This part is solved with the length contraction formula and the velocity calculated in the previous part (1). Moreover, we obtain: Using the result we got from (1), and plugging that velocity v and the fact that is equal to one hour, then es , and from this Substituting the numerical values, we obtain the given solution easily. 3) Simple application of time dilation formula provides: Inserting, in this case, our given velocity, we obtain the solution we wrote above: .

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