 Solution

ID: past-exam-of-the-physics-course-of-the-year-1-of-the-natural-sciences-course-of-the-university-of-cambridge/2024/paper-1/section-b/7/a/solution

u = \frac{v + u ^{'}}{1 + v u ^{'} / c ^{2}} .

With both velocities directed toward Earth,

u = \frac{0.6 c + 0.8 c}{1 + 0.48} = \frac{35}{37} c = 0.946 c .

The denominator keeps the result below

c

. Adding the two speeds by the Galilean rule would give an inadmissible

1.4 c

 New to topics? Read the docs here!