问题 实验题

在“测量盐水密度”的实验中:

(1)将天平放在水平桌面上,游码置于标尺左端的零刻度处,调节___________,使横梁平衡;

(2)在烧杯中倒入盐水,称出烧杯与盐水的总质量为75g;将烧杯中一部分盐水倒入量筒中(如图甲所示),则量筒内盐水的体积是___________cm3。再称量烧杯和剩下的盐水总质量时,发现加减砝码总不能使天平平衡,这时应移动___________使天平平衡;

(3)若天平再次平衡时所用的砝码、游码位置如图乙所示,则烧杯和剩下的盐水总质量是___________g,倒入量筒内的盐水质量为___________g;

(4)通过计算可知盐水的密度为___________kg/m3

(5)若某同学用天平和量筒测量盐水密度时的实验步骤是:

a.调好天平的平衡;

b.测量一个空烧杯的质量m1

c.烧杯装适量的盐水,测量烧杯与盐水的总质量m2

d.将烧杯中盐水倒入量筒中,测出盐水的体积V;

e.收拾好器材;

f.推导出盐水的密度ρ=___________。

小明认为这种测量盐水密度的方法误差太大,按这样的步骤测定盐水的密度,其测量结果将___________(填“偏大”或“偏小”)

答案

(1)平衡螺母

(2)20,游码

(3)54,21

(4)1.05×103

(6),偏大  

简答题

全国劳动模范徐虎,是一个水电维修工。他十几年如一日为居民解决水电急修的困难,把温暖送到千家万户,在平凡的岗位上做出了不平凡的成绩。他曾说:“你不奉献我不奉献,谁来奉献?你也索取我也索取,向谁索取?” 

                                                                                                                                                               

                                                                                                                                                               

                                                                                                                                                               

                                                                                                                                                               

                                                                                                                                                               

                                                                                                                                                              

问答题 简答题