When a capillary tube is place vertically in a liquid with sufficient length outside the liquid, the potential energy of  the liquid rised into the capillary tube is${\mathrm{U}}_1$. If another capillary tube same material but of half the radius of cross-section is placed similarly the potential energy  of liquid raised is ${\mathrm{U}}_2$  then ${\mathrm{U}}_1$ : ${\mathrm{U}}_2$ is