Eat Flashcards
Viscosity
the flow of a liquid, how fast a liquid flows
Low viscosity
runny
High viscosity
sticky, thick
Laminar Flow
At low velocities a fluid tends to flow without lateral mixing and adjacent layers slide past one another - liquid is streamlined, no abrupt changes in direction or speed
Stoke’s Law relies on
Laminar flow
Turbulent flow
different layers of fluid cross over and mix, there is changing speeds and directions and little eddies are formed throughout the path - this occurs when the rate of flow reaches a critical level or an obstacle is in the way
Thixotrophy
Normally it doesn’t flow but when a force is exerted on it the viscosity lessens and it flows. When the force is again removed the viscosity increases and it stops flowing again (e.g. margarine)
Negative thixotrophy
normally it flows but when a force is exerted on it it hardens
How to measure flow rates?
measure mass (mass flow rate) or volume (volume flow rate) collected in a time interval
Hard material
a material that is not readily scratched or indented (e.g. diamond)
Stiff material
- doesn’t easily change shape when a force is applied - large load causes small deformation
- doesn’t extend much (e.g. steel)
Elastic material
- retains original shape when stretched
- when an object returns to its original shape after the load is removed (e.g. rubber)
Plastic material
- extends irreversibly
- when an object is deformed and doesn’t return to its original shape after the load is removed
Ductile material
-can be drawn into wires (e.g. copper)
Malleable material
- can be deformed and moulded into shape with a force
- can be hammered into sheets (e.g. gold)
Strong material
- large force is required to make it break
- high breaking stress (e.g. steel)
Brittle material
- little force is required to crack and break it
- no plastic deformation (e.g. glass)
Tough material
- requires lots of force to break
- high energy density (e.g. mild steel, rubber tyres)