Determinism, rate independance and predictability

[Coz]

I can't figure out how to predict where a body will be after moving it.

Say, I want to move a body that has 100 kg of mass at a speed of 25 meters per second over 25 meters.

My program has a fixed Bullet timestep, but a variable logic timestep. So I figured that my formula would be:

force = mass x target_velocity x timestep

and use applyCentralForce(force).

But the body moves slowly. I haven't tried it, but I doubt that applyCentralImpulse() would be helpful here.

[Coz]

I think that the problem is that I don't need to multiply my force by the delta time, since I already passed the delta time to stepSimulation(), but I would like some confirmation about this.