Hello, I need to buy a DC motor for my project work. My project involves rotation of a cylindrical disk of 1 kg, inside water (approx. 2 cm below the water level) at different speed ranging between 100 rpm -200 rpm. For this purpose I need to buy a DC motor but I am not sure of what specification I really need. I have done calculation but I am little confused as I have no idea about these things. So please someone tell me what power and what torque I need for this purpose and exact specification of DC motor to buy. I also need to know how can I control DC motor to run at desired constant rpm. I need urgent help.