如图所示为“探究加速度与物体受力与质量的关系”实验装置图.图中A为小车,B为装有

题型:问答题

问题:

如图所示为“探究加速度与物体受力与质量的关系”实验装置图.图中A为小车,B为装有砝码的小桶,C为一端带有定滑轮的长木板,小车通过纸带与电火花打点计时器相连,计时器接50HZ交流电.小车的质量为m1,小桶(及砝码)的质量为m2

(1)下列说法正确的是______.

A.每次改变小车质量时,应重新平衡摩擦力

B.实验时应先释放小车后接通电源

C.本实验m2应远大于m1

D.在用图象探究加速度与质量关系时,应作a-

1
m1
图象

(2)实验时,某同学由于疏忽,遗漏了平衡摩擦力这一步骤,他测量得到的a-F图象,可能是图1中的图线______.(选填“甲”、“乙”、“丙”)

(3)如图2所示为某次实验得到的纸带,纸带中相邻计数点间的距离已标出,相邻计数点间还有四个点没有画出.由此可求得小车的加速度大小______m/s2.(结果保留二位有效数字)

考点:实验:探究加速度与力、质量的关系
题型:问答题

阅读理解。

     Everyone has a dream job and we all hope our dreams can come true. Mr Black works as a reporter

at a TV station. He wants to know what jobs teenagers are going to do when they grow up. He went to

the Evergreen School to do a survey (调查) last Friday.

     Mr Black asked the students to discuss with each other and then fill in the form with a pen. He told

them to tell the truth. Mr Black thought most students would be teachers. The techer is one of the best

professions (职业) in the world. Maybe some students would be scientists. Rich knowledge would help

them. A few students would be soldiers (士兵) because they could keep our country beautiful and

peaceful.

     Teachers helped Mr Black before school was over. They gave out one thousand eight hundred

papers to the students. When the survey's result came out, Mr Black and the teachers were surprised.

Please look at the results.

1. From the first paragraph, we know this passage may talk about _______.

A. teenagers' dream jobs            

B. Mr Black and his job

C. how dreams come true          

D. how to make a survey

2. What does Mr Black do?

A. He is a teacher.                

B. He is a reporter.

C. He is a soldier.                  

D. He is an actor.

3. Why did Mr Black do a survey last Friday?

A. Because he wanted to find a job for himself.

B. Because he wanted to know about students' dream jobs.

C. Because he was always interested in doing a survey.

D. Because he wanted to know how much money teenagers got a week.

4. Which of the following did most students choose?

A. Actor.                        

B. Sports player.

C. Teacher.                      

D. Scientist.

5. How many teenagers want to be teachers in the future?

A. 90.                          

B. 360.

C. 900.                        

D. 1800.

题型:问答题

下列作品中属周部族史诗的是()

A.《生民》

B.《公刘》

C.《绵》

D.《皇矣》

题型:问答题

为什么在外圆磨床上用前后固定顶尖装夹轴类工件可以提高加工精度

题型:问答题

与交感神经兴奋有关的心律失常宜选用:

A.苯妥英钠
B.利多卡因
C.普萘洛尔
D.普鲁卡因胺
E.胺碘酮

题型:问答题

下列原子序数中,易形成离子的是()。

A、6

B、9

C、11

D、13

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