Special Relativity question

[Reckoner]

If an observer on earth observes two spaceships travelling towards each other, one at 0.6c (A), the other at 0.7c (B), what speed would ship A measure B to be travelling at and vice versa?

Thanks

[yawho]

If an observer on earth observes two spaceships travelling towards each other, one at 0.6c (A), the other at 0.7c (B), what speed would ship A measure B to be travelling at and vice versa?

Thanks

diff lorentz transf wrt t to obtain a conversion formula
answer 0.9155c

[Reckoner]

ok, thanks. Do I need that formula/to know how to do this for VCE physics?

[yawho]

have not seen such questions in past exams

[Reckoner]

Ok, thanks a lot!