Assuming that B is directly below A, the change rule of shadow is: at first, when the stick stands upright, it is 0, that is, 1 min. With the inclination of the stick becoming longer, the shadow is the longest when the stick is inclined at 45 degrees, then it becomes shorter after 45 degrees, and finally stops at the length of the stick of 2 meters.
2. The wooden stick is perpendicular to the light, that is, the state that the wooden stick is inclined at 45 degrees in the question 1.
Here, it is assumed that the moving cross section of the wooden stick is point C, and the trajectory of point C is 1/4 arc when the wooden stick is inclined at 45 degrees. According to the principle that the tangent of a circle is perpendicular to its radius, it can be concluded that the wooden stick is perpendicular to the light at this time, and the shadow distance b of the tangent point on the ground is the longest. This is very simple to explain graphically, but it is too much to say when drawing.