Section outline

  • A pH meter on a table, measuring the acidity of a liquid solution.

    The device pictured above is called a meter. It is a scientific measuring device that measures the acidity of a . Being able to use scientific measuring devices such as this is an important science skill. That’s because doing science typically involves making many measurements. For example, if you do lab exercises in science, you might measure an object’s length or mass, or you might find the volume of a liquid. Scientists use sensitive measuring devices to make measurements such as these. The measurements are usually made using SI units of measurement.
    ::上面所描绘的装置称为计量仪。这是一个科学测量装置,测量一个物体的酸度。能够使用科学测量装置,这是一个重要的科学技能。这是因为科学工作通常涉及进行许多测量。例如,如果你在科学领域进行实验室练习,你就可以测量一个物体的长度或质量,或者你可能找到一个液体的体积。科学家们使用敏感的测量装置来进行这样的测量。测量通常使用SI的测量单位进行。

    Measuring Length with a Metric Ruler
    ::用米标尺测量长度

    You’ve probably been using a ruler to measure length since you were in elementary school. But you may have made most of the measurements in English units of length, such as inches and feet. In science, length is most often measured in SI units, such as millimeters and centimeters. Many rulers have both types of units, one on each edge. The ruler pictured below has only SI units. It is shown here bigger than it really is so it’s easier to see the small lines, which measure millimeters. The large lines and numbers stand for centimeters. Count the number of small lines from the left end of the ruler (0.0). You should count 10 lines because there are 10 millimeters in a centimeter.
    ::你可能从上小学以来就一直在使用标尺测量长度。 但你可能已经用英文长度单位(如英寸和英尺)做了大部分测量。 在科学方面,长度通常是用SI单位(如毫米和厘米)测量的。 许多标尺有两种类型的单位,每个边缘各一个。 下面的标尺只有SI单位。 标尺在这里显示的比实际显示的要大得多,所以比较容易看到小线,用来测量毫米。 大线和数字代表中米。 计算标尺左端的小线( 0.0 ) 。 您应该数十行, 因为一厘米内有10毫米。

    Metric ruler displaying millimeters and centimeters with a red line indicating 32 mm.

    Q: What is the length in millimeters of the red line above the metric ruler?
    ::问题:公尺尺以上红线的长度(毫米)是多少?

    A: The length of the red line is 32 mm.
    ::A:红线长度为32毫米。

    Q: What is the length of the red line in centimeters?
    ::问题:红线的长度是多少?

    A: The length of the red line is 3.2 cm.
    ::A:红线长度为3.2厘米。

    Measuring Mass with a Balance
    ::以平衡衡量质量

    Mass is the amount of matter in an object. Scientists often measure mass with a balance. A type of balance called a triple beam balance is pictured in Figure  . To use this type of balance, follow these steps:
    ::质量是物体中物质的数量。 科学家通常用平衡测量质量。 图中描绘了一种称为三束平衡的平衡。 要使用这种平衡,请遵循这些步骤:

    1. Place the object to be measured on the pan at the left side of the balance.
      ::将要测量的对象放在平衡的左侧的锅盘上。
    2. Slide the movable masses to the right until the right end of the arm is level with the balance mark. Start by moving the larger masses and then fine tune the measurement by moving the smaller masses as needed.
      ::向右滑动可移动质量, 直到手臂右端与平衡点保持平衡。 从移动较大质量开始, 然后根据需要移动较小质量, 微调测量 。
    3. Read the three scales to determine the values of the masses that were moved to the right. Their combined mass is equal to the mass of the object.
      ::读取三个比例尺以决定移到右边的质量值。它们的组合质量等于对象的质量。

    Triple beam balance showing scales for measuring mass, with an object on the pan.

    The Figure  is an enlarged version of the scales of the triple beam balance in Figure  . It allows you to read the scales. The middle scale, which measures the largest movable mass, reads 300 grams. This is followed by the top scale, which reads 30 grams. The bottom scale reads 5.0 grams. Therefore, the mass of the object in the pan is 335.0 grams (300 grams + 30 grams + 5.0 grams).
    ::图是图中三束平衡的扩大版。 它允许您读取尺度。 测量最大移动质量的中等尺度读取300克。 之后是最高尺度, 读取30克。 底尺度读取5. 0克。 因此, 锅中天体的重量为33.5万克( 300克+30克+5. 0克)。

    Enlarged scales of a triple beam balance showing readings of 300g, 30g, and 5g.

    Q: What is the maximum mass this triple beam balance can measure?
    ::问题:这种三光线平衡能测量的最大质量是多少?

    A: The maximum mass it can measure is 610 grams (500 grams + 100 grams + 10 grams).
    ::A:它能够测量的最大质量为610克(500克+100克+10克)。

    Q: What is the smallest mass this triple beam balance can measure?
    ::问题:三束平衡能测量的最小质量是多少?

    A: The smallest mass it can measure is one-tenth (0.1) of a gram.
    ::A:它可以测量的最小质量是一克的十分之一(0.1)。

    To measure very small masses, scientists use electronic balances, like the one in the Figure  . This type of balance also makes it easier to make accurate measurements because mass is shown as a digital readout. In the picture, the balance is being used to measure the mass of a white powder on a plastic weighing tray. The mass of the tray alone would have to be measured first and then subtracted from the mass of the tray and powder together. The difference between the two masses is the mass of the powder alone.
    ::为了测量非常小的质量,科学家使用电子平衡,如图中的平衡。这种平衡也使精确测量更加容易,因为质量显示为数字读数。在图片中,平衡用于测量塑料称重托盘上的白色粉末质量。仅托盘的质量必须首先测量,然后从托盘和粉末的质量中一起减去。两种质量的差异是粉末本身的质量。

    An electronic balance measuring the mass of white powder on a plastic tray.

    Measuring Volume with a Graduated Cylinder
    ::使用已毕业的圆柱体测量音量

    At home, you might measure the volume of a liquid with a measuring cup. In science, the volume of a liquid might be measured with a graduated cylinder, like the one sketched below. The cylinder in the picture has a scale in milliliters (mL), with a maximum volume of 100 mL. Follow these steps when using a graduated cylinder to measure the volume of a liquid:
    ::在家,您可以用一个测量杯测量液体的体积。在科学上,液体的体积可以用一个分级的气瓶来测量,像下面所绘制的气瓶那样。图片中的气瓶的尺寸为毫升,最大容量为100毫升。在使用分级的气瓶测量液体体积时,请遵循这些步骤:

    1. Place the cylinder on a level surface before adding the liquid.
      ::在添加液体之前先将气瓶放在水平表面。
    2. After adding the liquid, move so your eyes are at the same level as the top of the liquid in the cylinder.
      ::在添加液体后,移动,使你的眼睛与气瓶中的液体顶部水平相同。
    3. Read the mark on the glass that is at the lowest point of the curved surface of the liquid. This is called the meniscus.
      ::读取位于液体弯曲表面最低点的玻璃上的标记。 这称为 meniscus 。

    Graduated cylinder measuring 67 mL of liquid, showing meniscus reading method.

    Q: What is the volume of the liquid in the graduated cylinder pictured above?
    ::问题:上面所描绘的毕业圆筒中的液体量是多少?

    A: The volume of the liquid is 67 mL.
    ::A:液体的体积为67毫升。

    Q: What would the measurement be if you read the highest point of the curved surface of the liquid by mistake?
    ::问题:如果误读液体曲线表面的最高点,测量结果会是什么?

    A: The measurement would be 68 mL.
    ::A:测量量为68毫升。

    Resources
    ::资源

     

     

    Summary
    ::摘要

    • In science, length may be measured with a metric ruler using SI units such as millimeters and centimeters.
      ::在科学方面,长度可以用一个使用SI单位(如毫米和厘米)的公尺标尺测量。
    • Scientists measure mass with a balance, such as a triple beam balance or electronic balance.
      ::科学家测量质量时保持平衡,如三束平衡或电子平衡。
    • In science, the volume of a liquid might be measured with a graduated cylinder.
      ::在科学方面,液体的体积可以用一个毕业的气瓶测量。

    Review
    ::回顾

    1. Using the enlarged metric ruler segment shown below, what is the length of the blue line in centimeters?
      ::使用下文所示扩大的公尺标尺段,蓝线以厘米计的长度是多少?

    An enlarged metric ruler segment displaying a blue line for measurement.

    1. Assume that an object has been placed in the pan of a triple beam balance. The scales of the balance are shown below. What is the mass of the object?
      ::假设一个物体已放置在三束平衡的平板中。以下显示平衡的尺度。对象的质量是多少?

    An illustration showing a triple beam balance with weights indicating the mass of an object.

    1. How much liquid does this graduated cylinder contain?
      ::这个毕业的气瓶装了多少液体?

    Two graduated cylinders showing liquid measurement levels, with one displaying 40 mL.