搜题请搜索小程序“爱下问搜题”
问题 实验题

用落体法验证机械能守恒定律的实验中

（1）有下列器材可供选用：电磁打点计时器、铁架台（带铁架）、带铁夹的重物、复写纸、纸带、秒表、导线、开关、天平，其中不必要的器材是                                   ；

缺少的器材是                                        。

（2）供选择的重物有以下四个，应选择（       ）

A．质量为100g的木球

B．质量为10g的砝码

C．质量为200g的重锤

D．质量为10g的塑料球（3）若实验中所用重锤质量为m="1kg" ，打点纸带如图所示（O点为自由下落的起始点），打点时间间隔为0.02s，则记录D点时，重锤的速度vD=          ，重锤动能EKD=         。从开始下落起至D点，重锤的重力势能减少量为            J，因此可得出的结论是                                      。（结果均保留三位有效数字）

（4）根据纸带算出相关各点的速度v，量出下落距离h，则以v2/2为纵轴，以h为横轴画出的图象应是下图中的（         ）

答案

（1）秒表，天平；刻度尺，低压交流电源。

（2）C  （3）0.768/s；0.295J；0.301mJ；在忽略阻力的情况下，重锤机械能守恒；（4）C

阅读理解
任务型阅读。阅读下面短文，按要求完成短文后的各项任务。
     Once the colors of the world argued. All thought that they were the best and most important.
     Green said:"Clearly I am the most important. I am the sign of (1)______ and hope. I'm the color of grass,
trees and leaves. Without me, all animals would die."
     Yellow laughed:"You are all so serious. I bring (2)______ and warmth into the world. Every time people
look at a yellow sunflower, they start to smile (微笑). Without me there would be no fun."
     Orange shouted:"I am the color of (3)______ and strength. I have the most important vitamins (维生素).
Think of carrots, vegetables and oranges. When I appear in the sky, (4) everyone is shocked at my beauty
and nobody gives another thought to any of you."
     (5) Red couldn't stand it any longer,"I am the color of (6)_____ and bravery. I am willing to fight for a
cause. I bring fire (火) into the blood."
     Their voices became louder and louder. The thunder got angry and the rain started to pour. When they
became calm the rain said, "(7) You foolish colors. Don't you know that each of you is unique (独一无二)?
If you don't agree, just follow me." They did as the rain told them and together made the most beautiful
rainbow (彩虹).
任务一：用下列方框中所给词的适当形式完成文中（1）（2）（3）（6）四空，使其语意正确，逻
              辑合理。（每词限用一次，每空限填一词）
dangerous,     healthy,     happy,     life
任务二：将（4）处划线句子翻译成汉语。 
              ______________________________________________________________________________
任务三：将（5）处划线句子进行同义句转化。
              5. Red could stand it.
              ______________________________________________________________________________
任务四：将（7）处划线句子变成感叹句。 
              7. you colors are!
              ______________________________________________________________________________
任务五：8. Which of the following is the best title of the passage?
                  A. All the colors are foolish.
                  B. Getting united (团结) is important.
                  C. Every color is unique.
                  D. All the colors are excellent.
查看答案
计算题

某课外活动小组为测定当地石灰石中含碳酸钙的质量分数，取来了一些矿石样品，并取稀盐酸200g，平均分成4份，将四份不同质量的样品加入到四份稀盐酸中，进行实验，结果如下：

实验1234
加入样品的质量/g5101520
生成CO2的质量/g1．543．084．4m
 

（1）上表中m的数值是__________________；

（2）试计算这种石灰石矿中碳酸钙的质量分数。

（3）第三次反应后所得溶液的溶质质量分数是多少？
查看答案