2.1
What is the definition of a force?
A push or pull that makes an object change its movement or shape
Name 4 different types of bridges.
Beam bridge
Suspension bridge
Truss bridge
Arch bridge
What are internal forces? Name them.
Are forces that act within a structure.
Shear, tension, compression
What is the strongest 2D shape? What is the strongest 3D shape?
2D: Triangle
3D: Triangular Prism
What is a cantilever?
A beam that is only supported at one end.
What is magnitude?
This is the size of the force.
What is an external force? Explain and give one example.
This is a force that is applied on a structure by something else.
An example would be wind blowing on a tree.
What is compression? Give one example of using compression to our advantage.
Compression acts to squeeze an object or push parts within an object together. Ex. A spring, pogo stick.
What is a beam? What kinds of beams are there?
Is a flat structure that is supported at each end.
Simple beam
I beam
Girder or Box beam
What is a column? What do we call a beam that is placed between two columns?
A solid structure that can stand by itself. A beam placed between two columns is called a crossbeam.
What does direction have to do with forces?
Direction tells us what effect the force will have on an object.
Static load: the weight of a structure and non-moving loads, these forces stay the same
Dynamic load: an external force that moves or changes with time, a good example is wind.What is tension? What happens when there is too much tension? Give one example of using tension to our advantage.
Tension is a force that acts to stretch or pull something apart. If there is too much tension, an object could become longer or snap. Ex. Bungee cord, running shoes.
How does an arch support its load?
The force of the load is carried into the foundation, spreading it out.
Structural stress results when the combination of external and internal forces on a structure are very big, making it weaker.
What is the definition of a Newton and what is it used for?
A newton is the amount of force needed to hold up a mass of 100g
A Newton is the standard unit for measuring force
What is centre of gravity? How do we make a structure more stable?
Centre of gravity is the spot in an object where all its weight is evenly balanced.
To make a structure more stable we need a wide base, and we need to put the main mass closer to the ground.
What is shear? Give one example of a structure that needs to resist shear.
Shear is a force that acts to push parts that are in contact with each other in opposite directions. Ex. Airplanes
What is structural fatigue? What causes it? Give an example of what it looks like.
It is caused by internal forces.
Ex. Cracks
What is structural failure? What does it look like (Hint: 4 ways).
If I weigh 1300 kg, how many Newtons do I weigh?
13000 Newtons.
Because 1N is needed to hold up 100g, this means that to hold 1000g or 1kg we need 10N. So, 10N =1kg. To get the right answer, we multiply 1300 x 10 to get 13000 N.What is load performance?
This is how well as structure holds the load it was designed to carry. It is often expressed as the maximum weight a structure can carry or the weight at which it fails.
What are complementary forces? Give an example of how they work?
This is when different kinds of internal forces act on a structure at the same time. Ex. Bending, when you stand on a beam it bends into a U shape, at the top it is being compressed, at the bottom is is being stretched by tension.
Define the strength of a structure.
Define the stiffness of a structure.Strength of a structure: the load at which it fails.
Stiffness of a structure: the ability of a structure to withstand changing shape under a load.
What do we need to consider when building a stable structure?
(Hint: 2 things)
1. How can we reduce internal forces: shearing, compression, tension
2. What materials should we use for each part of the structure.