House Rules
1. Please clean up before leaving.
2. Showers to be taken before 11 p. m.
3. No staying out ’after 10p. m. unless allowed by me.
4. You may have incoming calls on my mobile phone but no out going calls.
5. Bed time is 11 p. m.
6. Dinner is at 7p. m. unless noticed. (通知). (If you don’t have dinner, you must let us know before 6 p. m. )
7. Keep noise to the least.
8. No smoking in the bedroom.
CB4 1LT
The address you are staying at is:
112 Kendal Way 
Chesterton
Cambridge
 Contact  numbers:
My mobile number  is
07870  347980

如图所示，轨道ABCD的AB段为一半径R=0.2m的光滑 $\frac{1}{4}$ 圆形轨道，BC段为高h=5m的竖直轨道，CD段为水平轨道．一质量为0.1kg的小球由A点从静止开始下滑到B点时速度的大小为2m/s，离开B点做平抛运动（g取10m/s²），求：