Answer
$0.53c$
Work Step by Step
We can determine the required relative speed as follows:
$v_2=\frac{v-v_1}{1-\frac{vv_1}{c^2}}$
We plug in the known values to obtain:
$v_2=\frac{0.77c-0.41c}{1-\frac{(0.77c)(0.41c)}{c^2}}$
$v_2=0.53c$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.