Materials Flashcards
What is Hookes Law?
The strain in a solid os proportional to the stress as long its within its elastic limits
What is the gradient of a force extension graph?
The spring constant
What is Hookes Law used to find?
The stiffness of a material
What does elastic behaviour mean?
This means that the material returns to its original shape once the deforming force has been removed
What is the area under a force extension graph?
This is the energy stored, shown by E=1/2Fx
What is the breaking point also called?
The strength of a material
What is the stress of a material?
This is the strength of a material
What does tensile mean?
When something is stretched
What does compress mean?
When something is squashed
How do you work stress out?
F/A
What is strain?
The relative change in shape
How do you work out strain?
extension/original length
What is young modulus?
The degree to which a material withstands change in length due to force
What also is young modulus?
A property of a material
How do you work out the young modulus?
Stress/Strain
How do you work out the young modulus from a graph?
Its the gradient of a stress strain graph
What is viscosity?
The measure of a fluids resistance to flow
What are the three tests used to measure viscosity?
Line spread test, Redwoods viscometer and the falling ball viscometer
What happens to the viscosity of a liquid when it is heated and why?
Becomes less viscous due to more particles vibrations, more vibrations means more kinetic energy
What happens to the viscosity of a gas when it is heated and why?
Becomes more viscous due to more particles colliding, more collisions means denser fluid
What is upthrust?
The weight of fluid displaced
What is density?
The measure of mass per m^3 of substance
Whats the equation for density?
P=m/V
How do you measure the density of an irregular shape?
Using an Archimedes jar and a top pan balance
How do you measure the density of a regular shape?
Top pan balance and ruler
How do you work out upthrust?
Upthrust=mg
What is laminar flow?
Where there are no mixing of layers resulting in a streamlined flow of fluid
What is turbulent flow?
Where there are abrupt changes of direction in the fluid that causes the slowing down of objects and the creation of Eddie currents
What is turbulence used for?
To reduce the rate of flow of a fluid
What is turbulence in terms of energy transfers?
The Ek of fluid is transferred to the Ek of the Eddie currents
What is stokes law used for?
To calculate the viscous drag force on an object moving through a fluid
What are the three requirements for stokes law?
- Small spherical object
- Low speeds
- Linear flow
What is the equation for stokes law?
F=6 x Pie x r(radius) x n(number of molecules) x v(velocity)
