Structures

Gravity is a force that plaques all efforts to build a structure that stands vertically off the ground. Gravity tends to pull objects towards the centre of the earth with a force proportional to the mass of the object. The challenge is to build stable structures that can perform the task they were designed for without succumbing to the many forces acting on them, such as wind and gravity.

But building stable structures is not all that difficult and if you look carefully around your neighborhood you will find many fine examples.
Houses are safe and stable structures designed to withstand wind and gravitational forces. The frame is the main structure that supports the building and can be considered as the skeleton of the house while the brick work is the skin and adds little to the stability of the structure.
The animal skeleton acts like the frame of a house. It supports the skin and internal organs, gives shape to the animal and distributes forces around the body to minimize stress and maximize power. The skeleton is not only a supporting structure but a working structure such as the cranes and forklifts used to lift huge loads.
Trees are very impressive natural structures that support a massive weight and grow to great heights against the force of gravity.
Bridges are built to withstand huge forces without bending and collapsing.
The Sydney Opera House is another famous structure, standing tall with unique shaped domes.

This tower at first glance would seem very unstable. It is very heavy at the top, but its design is such that this structure can withstand high winds and gravity with little effort.

Structures come in many forms, shapes and sizes with different designs. The common link between all these designs is that they spread the force acting on the structure across a wide area. If a force was allowed to concentrate in one area a fault may result and the structure may collapse or be severely weakened.

Consider the brick wall of a house. Stephen is pondering the stability of this structure and the reason why the bricks are not placed directly above each other. Why can we take a brick out of the wall without severely weakening the side of the house?

Solution

What would happen to the stability of the wall, if a brick was removed, from a wall that had the bricks placed directly above each other?

Solution
Continue with bridges