Answer:
0.345 c
Explanation:
[tex]v_{se}[/tex] = velocity of spaceship relative to earth = 0.95 c
[tex]v_{ts}[/tex] = velocity of torpedo relative to spaceship = - 0.90 c
[tex]v_{te}[/tex] = velocity of torpedo relative to earth
Velocity of torpedo relative to earth is given as
[tex]v_{te}=\frac{v_{se} + v_{ts}}{1 + \frac{v_{se}v_{ts}}{c^{2}}}[/tex]
[tex]v_{te}=\frac{0.95c + (- 0.90 c)}{1 + \frac{(0.95 c)(- 0.90 c))}{c^{2}}}[/tex]
[tex]v_{te}[/tex] = 0.345 c