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Glossary
deformation
change in shape due to the application of force
drag force
FDFD size 12{F rSub { size 8{D} } } {}, found to be proportional to the square of the speed of the object; mathematically
5.48 F D ∝ v 2 F D ∝ v 2 size 12{F rSub { size 8{D} } prop `v rSup { size 8{2} } } {}
5.49 FD=12Cρ Av2,FD=12Cρ Av2, size 12{F rSub { size 8{D} } = { {1} over {2} } Cρ ital "Av" rSup { size 8{2} } } {}
where CC size 12{C} {} is the drag coefficient, AA size 12{A} {} is the area of the object facing the fluid, and ρρ size 12{ρ} {} is the density of the fluid
friction
a force that opposes relative motion or attempts at motion between systems in contact
Hooke's law
proportional relationship between the force FF on a material and the deformation ΔLΔL it causes, F=kΔLF=kΔL size 12{F=kΔL} {}
kinetic friction
a force that opposes the motion of two systems that are in contact and moving relative to one another
magnitude of kinetic friction
fk=μkNfk=μkN size 12{f rSub { size 8{k} } =μ rSub { size 8{k} } N} {}, where μkμk size 12{μ rSub { size 8{K} } } {} is the coefficient of kinetic friction
magnitude of static friction
fs≤μsNfs≤μsN size 12{f rSub { size 8{s} } <= μ rSub { size 8{s} } N} {}, where μsμs is the coefficient of static friction and NN is the magnitude of the normal force
shear deformation
deformation perpendicular to the original length of an object
static friction
a force that opposes the motion of two systems that are in contact and are not moving relative to one another
Stokes' law
Fs=6πrηvFs=6πrηv size 12{F rSub { size 8{s} } =6πrηv} {}, where r r is the radius of the object, η η is the viscosity of the fluid, and v v is the object's velocity
strain
ratio of change in length to original length
stress
ratio of force to area
tensile strength
measure of deformation for a given tension or compression