(1) In this experiment, in order to verify the parallelogram law of force, the graphic method of force is adopted, and the resultant force, theoretical value and actual value are worked out, and then compared and obtained. Therefore, in the experiment, in addition to recording the instructions of the spring scale, we should also record the directions of two strings to determine the directions of two pulling forces, so as to make the drawing of pulling forces. In step e, pulling the node of rubber strip to position O is not explained.
(2) The direction of one of the forces remains unchanged, and its magnitude gradually increases. In order to keep the resultant force constant, the angle between another force and it needs to increase, then decrease and then increase, so choose B.
So the answer is: (1) Step e did not say to pull the node of rubber strip to position O.
(2)B