请您为广东省2026届高考目标为本科上线物理成绩中等的高三学生讲解这道物理题---**Question 7 (12 points)** **Question Stem:** Slides are games that children love to play. There are two straight slides AB and AC. Points A, B, and C are on the same circle in a vertical plane, and A is the highest point of the circle. The schematic diagram is shown in the figure. It is known that the radius of the circle is R. In the vertical plane where the circle is located, there is a position P, which is $\sqrt{3}R$ away from point A and is at the same height as A. The friction of all slides is negligible, and the acceleration due to gravity is known to be $g$. **Chart/Diagram Description:** * **Type:** Geometric figure / Schematic diagram. * **Main Elements:** * A dashed circle representing a circular path. * Points A, B, and C are located on the circumference of this dashed circle. * Point A is positioned at the top of the circle, indicating the highest point. * Points B and C are on the lower parts of the circle, with B on the left side and C on the right side relative to A. * Two solid straight lines, AB and AC, are drawn, representing the slides. These lines connect point A to point B and point A to point C, respectively. * Point P is located horizontally to the right of point A, outside the circle. * A dashed horizontal line connects A and P, indicating that point P is at the same height as point A. * The label P is adjacent to the point on the right. **Sub-question (1):** If a child starts from rest and slides down along AB and AC respectively, try to explain the relationship between the two sliding times by calculation. **Sub-question (2):** If a straight slide is designed with its upper end at point P and its lower end at some point on the circle, what is the shortest time for a child to slide down this slide from rest?