B$)$ A traffic light hangs from a pole, as shown in the figure. The uniform aluminum pole $AB$ is $7\mathrm{.}20$ m long and has a mass of $12\mathrm{.}0$ kg $.$ The mass of the traffic light is $21\mathrm{.}5$ kg $,$ as shown in the figure.

Determine:

$($a$)$ The tension in the $-$horizontal massless cable CD$,$

$($b$)$ The vertical and horizontal components of the force exerted by the pivot $A$ on the aluminum pole.

C$)$ i$)$ Which is more elastic, Copper or Rubber? Explain why.

ii$)$ Door handles are always kept at the side end of the door? Explain why.