(1) Draw a vertical downward line segment with an arrow after passing through point A, which is represented by symbol G; Draw a line segment with an arrow along the vertical direction at the contact point between the passer and the ground, which is represented by symbol F;

The fulcrum serves as the vertical section of the gravity action line and the vertical section of the supporting force action line, as shown in the figure:

(2) As shown in the figure, according to the lever balance condition F×L2=G×L 1,

Support from the ground to the hands:

f = l 1L2G = 2. 1cm 3cm×500n = 350n。

Answer: the supporting force of both hands is 350 n.