问题 填空题

利用图中所示的装置可以研究自由落体运动.实验中需要调整好仪器,接通打点计时器的电源,松开纸带,使重物下落.打点计时器会在纸带上打出一系列的小点.

(1)为了测得重物下落的加速度,还需要的实验器材有______.(填入正确选项前的字母)

A.天平        B.秒表        C.米尺

(2)实验中打下的一条纸带,O点是重物开始下落时打下的起点,该小组在纸带上选取A、B、C、D、E、F、G七个计数点,每两个计数点间还有一个计时点(图中未画出),各计数点与起点O的距离如图所示,已知打点计时器工作频率为50Hz,分别计算B、C、D、E、F五个计数点,则当地的重力加速度为______(结果保留3位有效数字).

答案

(1)时间可以从纸带直接得到,故需要刻度尺来测量长度;

(2)根据匀加速直线运动的特征公式△x=aT2,有

(DE+EF+FG)-(AB+BC+CD)=9aT2

带入数据得

a=

DG-AD
9T2
=
(0.5012-0.1959)-(0.1959-0.0314)
9×0.042
≈9.78m/s2

故答案为:(1)C,(2)9.67-9.94m/s2

阅读理解

This was not going to be a Mother’s Day as before. A lot of things had changed in the last few months. Usually we would give Mom flowers and take her out for a big meal. We couldn’t afford it this year.

Since I was born, Mom had been able to stay at home with me. We always had enough money to go out to eat two or three times a week if I had behaved well.

All that changed in January.

I could tell that Dad was getting a little angry. Mom would tell me to be quiet and let him rest at night. He’d work later and later.

Beginning in February, Dad tried hard to find another job. But it wasn’t easy for him to find something at the level he used to. He could not bring in as much money. That’s when he asked my mom to go back to work.

After a couple of weeks, Mom found a full-time job at a bank. The pay would be a big help to the family, but now Mom would not be around as much. I didn’t like it. I now had to stay in the after-school care program instead of going home and playing in my neighborhood. Too bad was, as soon as I did get home, I had to help get dinner ready, because Mom wouldn’t get home until after 6:00. I really missed the past time.

a)        This was not going to be a Mother’s Day as before because the writer’s father wasn’t in

b)       The writer’s home used to be rich. 

c)        His family changed because his father was mad.

d)       In February, the writer’s mother started to work at a bank.

e)        The writer really wanted his mother to stay with him

单项选择题 A1/A2型题