What do you know about the man
[A] He was not born in Beijing.
[B] His parents like Beijing better than he does.
[C] Beijing is the place where his parents were born.

如图是一个设计“过山车”的试验装置的原理示意图．斜面AB与竖直面内的圆形轨道在B点平滑连接．斜面AB和圆形轨道都是光滑的．圆形轨道半径为R．一个质量为m的小车（可视为质点）在A点由静止释放沿斜面滑下，小车恰能通过圆形轨道的最高点C．已知重力加速度为g．

求：

（1）A点距水平面的高度h；

（2）在B点轨道对小车的支持力的大小．