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.
Well, there would have to major supports on every building that was tall even though we have very strong foundation the foundation doesn't do anything except no give us dirt as a floor.but a really strong structure to use is a triangle formation.
Hope this helped
We are given that,

We need to find
when 
The equation that relates x and
can be written as,


Differentiating each side with respect to t, we get,



Replacing the value of the velocity


The value of
could be found if we know the length of the beam. With this value the equation can be approximated to the relationship between the sides of the triangle that is being formed in order to obtain the numerical value. If this relation is known for the value of x = 6ft, the mathematical relation is obtained. I will add a numerical example (although the answer would end in the previous point) If the length of the beam was 10, then we would have to



Search light is rotating at a rate of 0.96rad/s
T=2s
g=10m/s2
h=?
free fall: h=gt2/2
h= 10*4/2
h=40/2
h=20m