Velocities moving against each other cancel each other out. What is the velocity of an airplane that flies at 500 mph and then encounters a 50 mph headwind (wind going against the direction of the plane)?

Objects a and b are visible in the night sky. six months later they are still visible, but object b shows less parallax than object a. which object is closer? a. a b. b c. you would need to wait another six months in order to figure this out. d. you would need to know the objects' angular diameters in order to figure this out.