Why, when I set a bodys velocity directly, does it come up to speed slower when joined to other bodies?
What is likely happening is that you are setting the velocity of one body without also setting the velocity of the bodies that it is joined to. When you do this, you cause error in the system in subsequent time steps as the bodies come apart at their joints. The error reduction mechanism will eventually correct for this and pull the other bodies along, but it may take a few time steps and it will cause a noticeable “drag” on the original body. Setting the velocity of a body will affect that body alone. If it is joined to other bodies, you must set the velocity of each one separately (and correctly) to prevent this behavior.
