1. ( 20 points) Consider a liquid in a cylindrical container. At t=0, the container begins to rotate. Until the liquid to rotate as a rigid body, the elevation difference h between the center of the liquid surface and the rim of the liquid surface increases with time t. It has been known that h is a function of the angular velocity , the fluid density , the gravitational acceleration g, the container radius R, the fluid viscosity , and time t. First determine the minimum number of the dimensionless numbers describing this problem using the Buckingham Pi theorem, and then provide the dimensionless numbers. (You don't have to show the detailed processes of finding the dimensionless numbers because your solution will be graded based only on the accuracy of the dimensionless numbers.)