<p>If you lift an object weighing 50 Newtons with a force of 500 Newtons, based on Newton's action-reaction third law, does the object put a 500 Newton force back on you? That would be a force greater than the object's weight.</p>
<p>Yes, you would get an equal and opposite reaction. Think of fighter pilots - they routinely go through maneuvers that result in 5g forces. The aircraft presses on them with this large force, and they press right back.</p>
<p>Nope - it will only pull back with the same force as it's weight - 50 Newtons. The disparity is because either the force doing the lifting was not all in the y direction (which I'm assuming the weight is for the purpose of discussion) or acceleration of the object is taking place.</p>