Why are tall building provided with metallic rods, running from the top of building to the ground?

What happens to the P.E. when an elevator loses in coming down from the top of a building to a stop at the ground floor?/

Two stones of different sizes are dropped simultaneously from the top of a bulding.Which stone would reach the ground earlier?

A circus artist is climbing a 20m long rope, which is tightly stretched and tied from the top of a vertical pole to the ground. Find the height of the pole, if the angle made by the rope with the ground level is 30^@ (see fig.).

From a point P on the ground the angle of elevation of the top of a 10 m tall building is 30^@ . A flag is hoisted at the top of the building and the angle of elevation of the top of the flagstaff from P is 45^@ . Find the length of the flagstaff.

From a point P on the ground the angle of elevation of the top of a 10 m tall building is 30^@ .A flag is hoisted at the top of the building and the angle of elevation of the top of the flagstaff from P is 45^@ . Find the length of the flagstaff and the distance of the building from the point P. (You may take sqrt3 = 1.732)

A man runs across the roof-top of a tall building and jumps horizontally with the hope of landing on the roof of the next building which is of a lower height than the first. If his speed is 9 m/s, the distance between the two buildings is 10 m and the height difference is 9 m, will he be able to land on the next building?

A 1.5 m tall boy is standing at some distance from a 30 m tall budding. The angle of elevation from his eyes to the top of the building increasesfrom 30^@ to 60^@ as he walks towards the building. Find the distance he walked towards the building.

A telescope has an objective lens of focal length 200 cm and an eye piece with focal length 2 cm.If this teleescope is used to see a 50 metre tall building at a distance of 2 km,what is the height of the image of the building formed by the objective lens?