A wire is stretched so that its length is doubled. The longitudinal strain is:

Surface tension is responsible for the nearly spherical shape of small liquid drops.

Water rises to height $h$ in a capillary tube of radius $r$. If the radius is doubled (same tube material and liquid), the new height is:

The SI unit of surface tension is:

The terminal velocity of a sphere falling in a viscous fluid depends on:

According to Stokes' law, the viscous drag on a sphere of radius $r$ moving with velocity $v$ through a fluid of viscosity $\eta$ is: