An unstable particle at rest breaks up into two fragments
of unequal mass. The mass of the lighter
fragment is equal
to 2.30 ✕ 10−28 kg and that of
the heavier fragment
is 1.77 ✕ 10−27 kg. If the
lighter fragment has a speed of 0.893c after the
breakup, what is the speed of the heavier fragment?