Can be easily pulled out by tensile force into longer thinner shapes
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Define stiff
Doesn't change shape when a force is applied.
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Define tough
Able to withstand impact forces without breaking
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Define plastic
Remains deformed when the load is removed
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Define elastic
Returns to its original shape when the load is removed
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Define hard
Doesn't scratch or dent easily and is able to resist plastic deformation
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What is a tensile force?
A force that acts to pull or stretch out a material.
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What is a compressive force?
A force that causes an object to become squashed or compacted.
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Define strong
Able to withstand both tensile or compressive stress.
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On a stress-strain graph what is the yield point?
At the yield point the material suddenly starts to stretch without any extra load - it is the stress at which a large amount of plastic deformation takes place with a constant or reduced load.
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What is the limit of proportionality on a stress-strain graph?
The point at which the material stops obeying Hooke's law, but would still return to its original shape if the stress was removed.
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What is the elastic limit on a stress-strain graph?
The point at which the material starts to behave plastically - the material would no longer return to its original shape once the stress was removed.
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What is a fluid element?
A part of the fluid in which all the particles are flowing in the same direction at the same rate (with the same velocity)
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What is a flow line?
The path that a particular fluid element follows.
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A stable flow line is called...
a streamline.
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What is laminar flow?
Laminar flow is a flow pattern where all the fluid elements flow in the same direction. The streamlines run parallel to each.
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When does laminar flow usually occur?
When a fluid is moving slowly.
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What is turbulent flow?
A flow pattern where the fluid elements get mixed up - you cannot draw streamlines because the flowlines are unstable.
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When does turbulent flow occur?
When a fluid is flowing quickly.
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What is viscous drag?
The force of friction produced by a flowing fluid when fluid elements with different velocities move past eachother.
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What does the viscous drag depend on?
The viscosity of the fluid.
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What does Stokes law help us to calculate?
The force due to viscous drag on a spherical object moving through a fluid.
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What is upthrust equal to?
The weight of fluid displaced.
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What happens to the spring constant and extension of a spring when it parallel with another spring?
The spring constant doubles and the extension will be halved.
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What happens to the spring constant and extension of two springs in series?
The spring constant halves and the extension doubles.
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What is the effect of stress on a material?
To pull the atoms apart from one another.
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What is the ultimate tensile stress of a material?
This is the maximum stress that the material can withstand.
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How do we find the elastic strain energy on a force extension graph?
Calculate the area under the graph.
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What is a Young's Modulus for a material?
The stress divided by the strain (the gradient on a stress strain graph)
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