Materials Flashcards
When would stoke’s law apply?
To small spherical objects in laminar flow and in a constant temperature
Why wouldn’t stoke’s law be best to use for larger spherical objects?
It may be less accurately calculated
What is upthrust equal to
the weight of fluid displaced
What is plastic deformation?
Where a material permanently deforms and won’t go back to its original shape once the force is removed
What is elastic deformation?
Where the material will go back to its original shape when force is removed
What is inelastic deformation?
where an object is stretched beyond its elastic limit
Out of the three states of matter, what 2 are fluids?
Gases and Liquids
How do you work out the circle circumference?
2PiR
How do you work out sphere surface area?
4pir2
How do you workout frequency?
1/time period
How are the atoms acting in the elastic region?
The atoms experience a slight force changing their shape, once released the electrostatic forces pull the atoms into equilibrium
How are the atoms acting when in plastic formation?
They move as layers that slide over each other with no restorative forces
What is strain?
The extension due to a material from its original length
What is the formula for strain?
Extension/Origninal length
What is the formula for stress?
Force/Cross-sectional area
How is tensile stress caused?
By stretching
How is compression forced?
By squashing
What are the units for Stress?
Pa or NM*2
What is the difference between stress and pressure?
Pressure is external and stress is internal
What’s the definition of strain?
The extension of the material from its original length. Caused by stress
What is young modulus?
It is a constant of proportionality that shows the stiffness of a material
Why doesn’t strain have units?
It’s a percentage/ratio
What is the definition of strong?
A material with a high breaking stress
What is the definition of hard?
A material which is hard to dent on the surface like Diamond.
What is the definition of ductile?
Can be readily drawn into wires
What is the definition of malleable?
Can be hammered into sheets of metal
State Archimedes principle
When a body is partly or fully immersed in water it experiences an upthrust equal to weight of fluid displaced
What is the formula linking force weight and upthrust?
F= W-U
A spherical bubble of 0.2 mm under water has a volume of 3.35x10-8
The density of air is= 1.2kgm-3
The density of water= 1.0x10-3kgm-3
Calculate the weight of the bubble
Calculate the upthrust of the air bubble
Weight= MxGfs Mass= 1.2 x 3.35x10-8 = 4.02x10-8 Weightb = 4.02x10-8 x 9.81= 3.9x10-7
Upthrust = weight of displaced fluid
Mass b in water= (1.0x10-3) x (3.35x10-8) = 3.35x10-5
Weight= 3.35x10-5 x 9.81 = 3.3x10-4
Upthrust = (3.3x10-4) - (3.9x10-7) = 3.3x10-4 N
What is an equation for upthrust?
Upthrust = density x volume x Gfs U = pVg
What is laminar flow?
When a fluid flows in parallel layers with no disruption
What is turbulent flow?
When a fluid moves chaotically with changes in pressure and direction and fluid velocity
What does the limit of proportionality mean?
The point beyond where Hooke’s law no longer is true
What does elastic limit mean?
The maximum extent a solid may be stretched without permanent alteration
What does yield point mean?
The stress beyond which a material becomes plastic
What is viscosity?
The resistance of a fluid flowing
