Combine each of the following groups of variables into a single dimensionless group, a p-term.
(a) Velocity V, length l, gravity g, and density r
(b) Velocity V, diameter D, density r, and viscosity m
(c) Velocity V, density r, diameter D, and kinematic viscosity n
(d) Angular velocity O, gravity g, diameter d, and viscosity m
(e) Angular velocity O, viscosity m, distance b, and density r
(f) Power WW_ ; diameter d, velocity V, and pressure rise Dp