平台离水平地面的高度为H=6m，平台的右上角有一光滑的 $\frac{1}{4}$ 圆弧AB，过B 的切线水平．C为B在水平面的投影，一个质量m=2kg的小球从A点由静止开始释放，g=10m/s²．求：

阅读短文，根据短文内容，选择正确答案。

Bob: Hello, Candy! What are you going to do on Sunday?

Candy: Oh, I'm going to the park to have a picnic.        

Bob: Do you like having a picnic?

Candy: Yes, I do. What about you?

Bob: Me, too. But my favourite hobby is playing computer games.

I think it's very fun.

Candy: D o you want to go with us?

Bob: Sure. What time?

Candy: At 8:00 o'clock tomorrow.

Bob: OK. See you later.

Candy: See you.

研究液体压强的实验分步进行，如图所示是实验中的某一步．若实验中液体的密度不变，从实验中的这一步可得出的结论是（　　）