The differential pressure in a U-tube manometer is given by:
\[
\Delta P = \rho g h
\]
where \( \rho \) is the density of mercury, \( g \) is the acceleration due to gravity, and \( h \) is the height difference.
Given:
\[
\rho = 13600 \, \text{kg/m}^3, g = 9.81 \, \text{m/s}^2, h = 0.01 \, \text{m}.
\]
Substituting the values:
\[
\Delta P = 13600 \times 9.81 \times 0.01 = 1333 \, \text{Pa}.
\]
Thus, the differential pressure is \( 1333 \, \text{Pa} \).