1. Stability and Centre of Gravity

2. If we think about simple principles that we see in everyday life, we can conclude that objects are more ____________ if they rest on a ____________ ____________ and have most of their ____________ close to the ____________. This is why football players are coached to keep their stance __________ ________ __________.
stable
large
area
mass
ground
“wide
and
low”

3. When we are thinking about making structures stable, the same principles apply. We think about a structure’s ____________ of gravity. An object’s centre of gravity is the point upon which the object will _________. In other words, the force of gravity from this point in all directions is _________.
centre
balance
equal

4. A structure is most stable when its centre of gravity is directly above its ____________. There is an imaginary, perpendicular line passing through the centre of gravity called a ____________ __________ which shows how the structure’s ____________ presses straight down from its centre of gravity. When the thrust line passes inside the ____________, then all sides of the base help to support the weight. If it passes outside the base then a structure can ____________.
base
thrust
line
weight
base
fail

5. inside of base
outside of base