Sumário

Glossary

drag force: $F_{D} F_{D} size 12{F rSub { size 8{D} } } {}$ , found to be proportional to the square of the speed of the object; mathematically
$F_{D} \propto v^{2} F_{D} \propto v^{2} size 12{F rSub { size 8{D} } prop `v rSup { size 8{2} } } {}$

$F_{D} = \frac{1}{2} Cρ {Av}^{2}, F_{D} = \frac{1}{2} Cρ {Av}^{2}, size 12{F rSub { size 8{D} } = { {1} over {2} } Cρ ital "Av" rSup { size 8{2} } } {}$
where $C C size 12{C} {}$ is the drag coefficient, $A A size 12{A} {}$ is the area of the object facing the fluid, and $ρ ρ size 12{ρ} {}$ 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 $F F$ on a material and the deformation $Δ L Δ L$ it causes, $F = k Δ L F = k Δ L size 12{F=kΔL} {}$

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: $f_{k} = μ_{k} N f_{k} = μ_{k} N size 12{f rSub { size 8{k} } =μ rSub { size 8{k} } N} {}$ , where $μ_{k} μ_{k} size 12{μ rSub { size 8{K} } } {}$ is the coefficient of kinetic friction

magnitude of static friction: $f_{s} \leq μ_{s} N f_{s} \leq μ_{s} size 12{f rSub { size 8{s} } <= μ rSub { size 8{s} } N} {}$ , where $μ_{s} μ_{s}$ is the coefficient of static friction and $N N$ 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: $F_{s} = 6 πrηv F_{s} = 6 πrηv size 12{F rSub { size 8{s} } =6πrηv} {}$ , 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

tensile strength: the breaking stress that will cause permanent deformation or fraction of a material