The "objective" (lens or mirror) is the major major major part of
the optical telescope. It's really the only part you need in order
to make a telescope (besides something to hold the objective).
You can put a piece of film or a CCD right at the focal point of
the objective lens or mirror and capture 'images' (pictures) there.
If you want to use the telescope for looking through and seeing stuff
with your eye, then you need the other major part ... the eyepiece lens.
Answer: 6.24 km
Explanation:
Given
The magnitude of the first vector(say) 
the magnitude of the second vector(say) 
the angle between them is 
The resultant vector magnitude is given by
With that information, you can determine the object's speed.
Just divide the distance covered by the time to cover the distance.
If you also know the direction the object moved, then you can
determine its velocity. If you don't, then you can't.
I'm not quite sure what happens to Fay so I didn't finish but hope it helps
