Reference Frames: True/False?

Which of the following statements are true?


1. Within a certain reference frame, two objects are each traveling with almost the speed of light, in opposite directions, and toward each other. Within that frame, their relative velocity is also almost the speed of light.


2. All three velocities in the formula for relativistic velocity addition are measured within the same reference frame.


3. If any one of the two velocities in the formula for relativistic velocity addition is c, the result is always c.


4. A spaceship is approaching a star with 0.4c. Seen from within the spaceship, the light from the star is moving with 1.4c.


5. Within a certain reference frame, two objects are reach traveling with 0.1c, in opposite directions, and toward each other. The observed speed with which they approach is approximately the same as would be seen from one of the objects.

Reference Frames: True/False?
1. True


2. True


3. True


4. False


5. True