将一测力传感器连接到计算机上就可以测量快速变化的力，图甲中O点为单摆的悬点，现将小球(可视为质点)拉到A点，此时细线处于张紧状态，释放摆球，则摆球在竖直平面内的ABC之间来回摆动，其中B点为运动中最低位置。∠AOB＝∠COB＝α，α小于10°且是未知量，图乙表示由计算机得到细线对摆球的拉力大小F随时间变化的曲线，且图中t＝0时刻为摆球从A点开始运动的时刻，据力学规律和题中信息(g取10m/s²)，求：

(1)单摆的周期和摆长； (2)摆球质量及摆动过程中的最大速度.

补全对话。

A: Do you know we have a new teacher and two new students this term?

B: Really? What does the new teacher look      l      ?

A: He is an old man. He      2      no hair.

B: Is he bald?

A: Yes. And he      3      glasses.

B:      4      he have a mustache?

A: No, he _   5     a beard. He is not good looking, But he is very kind.

B: What      6     your new classmates? What      7     they __ 8     like'?

A: They are twins. They look the     9    .They    10    of  medium height. They're not heavy _  11     thin,

They _  12     curly hair.

B: What's the     13          14     their hair ?

A: Well, they     15      blonde hair. They are good-looking