I'm sure I'm not thinking of this the right way. I'm hoping someone can see the error in my logic. Should a force have less of an impact on a moving object than one which is at rest? An object which is in motion has a momentum given by p=mv. A force F acting (say in the opposite direction) on this object need to overcome the object's momentum. The same force acting on an object at rest needs not overcome any momentum (thought I guess the object here has inertia). So wouldnt it make sense for the force to have more of an effect on the object which was at rest than one which was in motion? (By 'effect' I suppose I mean difference between initial and final velocities vf-vi) If this is not the case, then does it mean inertia and momentum are the same thing?