For an overview on creating, visualizing, and simulating mover constraints, including Torque, see Mover Constraints. Also see Roblox Units to understand how Roblox units compare to metric units.
A Torque constraint applies constant torque on an assembly from its center of mass.
Because the Torque constraint applies constant torque and angular acceleration, very high speeds may result if no other forces are involved. If you want to maintain a more steady velocity over time, use an AngularVelocity constraint. Alternatively, if you only need initial velocity, set the AssemblyAngularVelocity property directly on the assembly.
Relativity
By default, torque is applied relative to Attachment0. If the parent assembly rotates, the torque will change direction to match the adjusted orientation of the attachment.
If RelativeTo is set to World, torque will be applied in world coordinates, independent of the parent or attachment orientations.
If RelativeTo is set to Attachment1, torque will be applied relative to Attachment1 and, if the attachment rotates, change to match its orientation.