How to resolve force required to rotate body ?

Hi,
I have to resolve force required to rotate platform about the pivot. Platform is around 700×700 mm size, weight is 45kg, one end connected to pivot.distance between Cg and pivot is 600mm. I have to resolve force required to rotate platform at multiple location. What is best method to get force value,? I want max force when it rotate to 90 degree.
What type of analysis should I use, either dynamic or static, how to get range of force for 90 degree rotation.