3.4 Materials Flashcards
3.4.1 Springs, 3.4.2 Mechanical properties of matter, (15 cards)
What is elastic deformation?
Material returns to original shape and size once forces on it are removed.
What is plastic deformation?
Material remains permanently deformed, and doesn’t return to its original shape and size once forces are removed.
What is the elastic limit?
Springs and other materials deform elastically up to a point, then plastically deform beyond that point
What does Hooke’s law state?
Extension of a spring is directly proportional to the force exerted on it as long as the limit of proportionality has not been exceeded.
what does a larger value of k in F= kx mean?
stiffer spring
what does it mean if the loading and unloading lines on a force extension graph are the same?
all the stored elastic pe is transferred back into external stores (e.g Ke, Gpe) when the force is removed.
what does it mean if the loading and unloading lines on a force extension graph are not the same?
Some energy remains in the internal store of the material. Area between the lines gives the amount of energy remaining in the internal store.
What happens when springs are in parallel?
combination is stiffer than each spring as they share the load, so same force causes less extension.
What happens when springs are in series?
combination is less stiff than each spring as each spring experiences the full load, so the same force causes more extension.
what is the tensile stress?
force stretching it divided by cross sectional area.
what is the tensile strain?
objects extension divided by original length
What does Young’s Modulus measure?
stiffness of a material.
equation for YM?
YM= stress/stain or YM=FL/Ax
what is the ultimate tensile stress?
maximum stress experienced by a material
what is the breaking point?
stress at which a material breaks
