Sections
Glossary
Glossary
 deformation
 change in shape due to the application of force
 drag force

${F}_{\text{D}}$, found to be proportional to the square of the speed of the object; mathematically
5.48 $${F}_{\text{D}}\propto {v}^{\text{2}}$$5.49 $${F}_{\text{D}}=\frac{1}{2}\mathrm{C\rho}{\mathrm{Av}}^{2},$$where $C$ is the drag coefficient, $A$ is the area of the object facing the fluid, and $\rho $ 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 $F$ on a material and the deformation $\mathrm{\Delta}L$ it causes, $F=k\mathrm{\Delta}L$
 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
 ${f}_{\mathrm{k}}={\mu}_{\mathrm{k}}N$, where ${\mu}_{\mathrm{k}}$ is the coefficient of kinetic friction
 magnitude of static friction
 ${f}_{\mathrm{s}}\le {\mu}_{\mathrm{s}}\phantom{\rule{0.25em}{0ex}}N$, where ${\mu}_{\mathrm{s}}$ is the coefficient of static friction and $N$ 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
 ${F}_{\mathrm{s}}=6\mathrm{\pi r\eta v}$, where $r$ is the radius of the object, $\eta $ is the viscosity of the fluid, and $v$ 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