Answer: The value of the force that the iOLab system measures depends on how you pick up the device using the spring or the eye bolt. If you pick up the device by the spring, the force probe will measure the tension in the spring, which is equal and opposite to the weight of the device. The value of this force will be negative, since it is directed downward. If you pick up the device by the eye bolt, the force probe will measure zero, since there is no force applied to it. The value of this force will be zero, since it is directed nowhere.