Materials Flashcards
How do you calculate absolute uncertainty?
half the range in repeats
OR
the precision
(whichever is largest)
How do calculate percent uncertainty?
(absolute uncertainty)/(mean value) x 100
Define Hooke’s law
the extension of a spring is directly proportional to the applied force up to the limit of proportionality
What comes first, the limit of proportionality or the elastic limit?
the limit of proportionality
What happens after the limit of proportionality in a F vs ΔL graph?
the line begins to level off
What the the area underneath a F vs ΔL graph show?
the elastic potential energy stored
What happens to the spring constant if there are two springs in series?
it halves
What happens to the spring constant if there are two springs in parallel?
it doubles
Which is easier to stretch, two springs in series or two springs in parallel?
two springs in series
Define spring constant
the force required to extend a spring 1m
Define tensile stress
the tension per unit cross-sectional area of a material
Define tensile strain
the extension per unit original length
What form must strain be in so that it can be used in a question?
decimal form (NOT as a percent)
What does Young’s modulus measure?
the stiffness of a materiel
Why do we use Young’s modulus?
It is independent of dimensions
What does a large plastic region on a stress-strain graph mean?
the material is ductile
What does a little plastic region on a stress-strain graph mean?
the material is brittle
How can you find Young’s modulus from a stress-strain graph?
the gradient of the linear region
What does the area underneath a stress-strain graph equal?
the energy stored per unit volume
How can we find ultimate tensile strength from a stress-strain graph?
the highest point of the graph
What do you do to uncertainties when quantities are multiplied or divided?
add the percent uncertainties
What do you do to uncertainties when quantities are add or subtracted?
add the absolute uncertainties
What is the yield point?
the stress at which a large amount of plastic deformation takes place with a constant or reduced load
