Topic 3
What is mass
Mass is the measure of how much matter or "stuff" we have in an object, how many molecules and atoms there are.
A bird flies into a window, is this an example of internal, or external force acting on a structure?
External
When two forces act in opposite directions we call this
Shear
The strongest shape for designing structures
Triangle
Point around which a falling object will rotate
Center of gravity
What is weight?
Weight is a measure of the force of gravity acting on an object
People coming and going are an example of this type of load acting on a structure.
Live load
Bend or buckle
Name for the stone at the top of an arch
Keystone
Name for the force felt on a wheel in motion
Spin stabilization
What are the units for mass? What about weight? (need both to count)
Answer will vary mass is g kg lbs, weight is measure in newtons
Name the four main types of internal force we discussed AND the 5th type which is really a special case of two of these occurring at once.
Tension Shear
Compression Torsion
Bend**
Something breaks due to being twisted too far
Torsion
A sturdy base with a long extension, often used for bridges
Cantilever
Metal or concrete poles driven deep into the ground to find solid bedrock
Pilings
If something like a pencil has a mass of 2700g, how much does it weigh?
26.487 N
What is the name for the failure caused when a metal gets worn out and breaks?
Metal fatigue
Areas of a car designed to break
Crumple zone
Helps hold up a shelf
Brace
Concrete platforms built in the ground for a structures walls to sit on
Footings
What two things affect the strength of gravity between two objects?
The size of the objects
The distance between the objects
Steel, graphite, and rubber are all made of carbon. What makes these substances so different from one another?
The way their molecules are arranged gives them different properties.
This device allows a cheaper more replaceable part of a motor to be broken while saving the engine itself from serious damage
Shear pin
Name for the force required to hold nails and screws in a material so that they structure will not just slip apart
Friction
Falls over