College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 30

An unstable particle at rest breaks up into two fragments of unequal mass. The mass of the lighter fragment is equal to 2.50 × 10 28 kg and that of the heavier fragment is 1.67 × 10 27 kg. If the lighter fragment has a speed of 0.893 c after the breakup, what is the speed of the heavier fragment