<s id="A18-1.22.01">[22] If we now want to lift a load to a higher place, we need a force equal to the load.</s>
<s id="A18-1.22.02">Let us assume a mobile pulley, fixed in height, perpendicular to the plane, which can easily be moved around the centers on an axle.Let there be lying around its rim a rope, one of whose ends is fastened to the load; let the other one be with the pulling force.Now I say that this load can be moved by a force equal to it.</s>
<s id="A18-1.22.03">Let there be on the other end of the rope not a force, but another weight attached, so it will show that the pulley, if the weights are equal, does not move towards any side and that the first weight is not strong enough for the second fastened one, nor the weight for the load, because the second fastened weight is equal to the first load.</s>
<s id="A18-1.22.04">If however a small amount is added to the weight, then the other weight is pulled upward.If therefore the force moving the load is larger than the load, then it is strong enough for it and moves it except if friction occurs in the turning of the pulley or stiffness of the ropes, so that it would cause a hindrance for the motion.</s>
