(2008? Longyan) As shown in the figure, put a ball with a weight of 2N on a smooth horizontal surface. After the ball is ejected with a finger with a force of 3N, the ball will move at a uniform speed to the right. The ball is subjected to vertical downward gravity and vertical upward supporting force, which are equal balance forces, both 2n; The point of action of these two forces is drawn on gravity, which is the center of the ball.

In addition, for the force diagram, the scale of 1N has been given, so the length of gravity and supporting force should be twice as long as the scale.

So the answer is as follows: