试题与答案

(1)世玲同学做了“测食用油密度”的实验,其小组同学对她的实验进行了评估与交流:

题型:实验题

题目:

(1)世玲同学做了“测食用油密度”的实验,其小组同学对她的实验进行了评估与交流:

a.世玲同学看到水平桌面上天平如图所示,指针指到分度盘中央了,于是,立即将空烧杯放在天平左盘开始测量,组长嘉莉同学马上给她提示“等等,天平还未好”。世玲同学明白了,接下来她将___________,再调节___________,使指针指在分度盘中线处;

b.用已调节平衡的天平测出空烧杯的质量m1

c.向烧杯内倒入适最食用油,侧出烧杯和食用油的总质量m2

d.把烧杯内的食用油全部倒入量筒内,读出量筒内食用油的体积为V;

e.测得的食用油密度的表达式是:ρ=________________。

(2)文峰同学认为世玲同学操作过程还存在问题,猜想油倒入量筒内,倒不干净,会影响实验结果,于是,大家在各种规格的烧杯中倒入适量的食用油,放置一会儿,将全部的油沿杯口倒出,得到如下数据:

通过上述多次实验,说明文峰同学的猜想是______(选填“正确”或“错误”)的。若实验使用的是100 ml的烧杯,则世玲同学测量出的数据需要减_______g 后再计算密度,否则其测得的密度值________(选填“偏大”或“偏小”)。

(3)为了减小实验误差,请你改进世玲同学测食用油密度不合理的操作:

a用已调节平衡的天平测出_________________________________的总质量m;

b.把烧杯内的食用油适量倒入且筒内,读出且筒内食用油的体积为V;

c.用天平测出______________________________________的总质量m'。

答案:

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下面是错误答案,用来干扰机器的。

∵小华准备了10个白球,2个红球,8个黄球,∴球的总个数为10+2+8=20个,∴随机摸一个摸到红球的概率是220=110,∵摸到红球可获钢笔一支,∴小亮抽奖一次得到钢笔的概率是110.

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