frame S, and the Earth reference frame S’. The velocity of the Earth relative to spaceship 2 is v = 0.60c. The velocity of spaceship 1 relative to the Earth is u′ x= 0.60c. Solve for the velocity of spaceship 1 relative to spaceship 2, u, using Eq. 36-7a. ux = u′ x +v 1+ vu′x c2 = 0.60c+0.60c 1+0.60 0.60 = 0.88c. (b) Now consider