Section outline

  • A person skateboarding down a steep ramp in a skate park.

    It’s exciting to roll down a skateboarding ramp, especially if you’re going fast. The steeper the ramp, the faster you’ll go. What else besides the steepness of a ramp influences how fast an object goes down it? You could do experiments to find out.
    ::滚下滑板坡路是令人兴奋的,特别是在你走得很快的情况下。 斜坡越陡,你走得越快。 除了斜坡的陡坡路程影响物体滑落速度之外,还有什么影响呢?你可以做实验来找出答案。

    What is an Experiment?
    ::什么是实验?

    An experiment is a controlled scientific study of specific variables. A variable is a factor that can take on different values. For example, the of an object down a ramp might be one variable, and the steepness of the ramp might be another.
    ::实验是对特定变量的受控科学研究。变量是一个可以取用不同值的因素。例如,斜坡下方对象可能是一个变量,斜坡的陡度可能是另一个变量。

    Experimental Variables
    ::实验变量

    There must be at least two variables in any experiment: a manipulated variable and a responding variable .
    ::在任何实验中必须至少有两个变量:一个被操纵变量和一个响应变量。

    • A manipulated variable is a variable that is changed by the researcher. A manipulated variable is also called an independent variable .
      ::被操纵变量是研究人员改变的变量。被操纵变量也称为独立变量。
    • A responding variable is a variable that the researcher predicts will change if the manipulated variable changes. A responding variable is also called a dependent variable .
      ::响应变量是一个变量,当被操纵的变量变化时,研究人员预测该变量将发生变化。响应变量也称为依附变量。

    You can learn how to identify manipulated and responding variables in an experiment by watching this video about bouncing balls:
    ::您可以通过观看关于弹跳球的视频, 学习如何在实验中辨别被操纵和响应变量:

     

     

    Q: If you were to do an experiment to find out what influences the speed of an object down a ramp, what would be the responding variable? How could you measure it?
    ::问题:如果你做一个实验 来找出什么影响物体在斜坡下的速度, 反应变量会是什么?你如何测量它?

    A: The responding variable would be the speed of the object. You could measure it indirectly with a stopwatch. You could clock the time it takes the object to travel from the top to the bottom of the ramp. The less time it takes, the faster the average speed down the ramp.
    ::A: 响应变量是对象的速度。 您可以用一只手表间接测量它。 您可以按时间将对象从坡道的顶部移动到底部。 时间越少, 坡道的平均速度越快。

    Q: What variables might affect the speed of an object down a ramp?
    ::问题:什么变量会影响对象下坡道的速度?

    A: Variables might include factors relating to the ramp or to the object. An example of a variable relating to the ramp is its steepness. An example of a variable relating to the object is the way it moves—it might roll or slide down the ramp. Either of these variables could be manipulated by the researcher, so you could choose one of them for your manipulated variable.
    ::A:变量可能包括与斜坡或对象有关的因素。与斜坡有关的变量的一个实例是斜坡的陡度。与对象有关的变量的一个实例是它移动的方式——它可能会滚动或滑下斜坡。这些变量中任何一个都可以由研究人员操纵,这样你就可以选择其中的一个变量作为你操控的变量。

    Controlling Variables
    ::控制变量

    Assume you are sliding wooden blocks down a ramp in your experiment. You choose steepness of the ramp for your manipulated variable. You want to measure how changes in steepness affect the time it takes a block to reach the bottom of the ramp. You decide to test two blocks on two ramps, one steeper than the other, and see which block reaches the bottom first. You use a shiny piece of varnished wood for one ramp and a rough board for the other ramp. You raise the rough board higher so it has a steeper slope (see sketch below). You let go of both blocks at the same time and observe that the block on the ramp with the gentler slope reaches the bottom sooner. You’re surprised, because you expected the block on the steeper ramp to go faster and get to the bottom first.
    ::假设你在实验中将木质木块滑下坡道。 你选择斜坡的斜坡陡峭度, 供您操作的变量使用。 您想要测量陡坡度的变化如何影响它到达坡道底部所需的时间。 您决定在两个坡道上测试两个街区, 一个比另一个更陡峭, 并且先看哪个块到达底部 。 您在一个坡道上使用一块光亮的清漆木块, 另一坡道上使用一块粗板。 您将粗板抬高, 使其有一个更陡坡的斜坡( 见下文的草图 ) 。 您同时放低的两块, 并观察坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡坡。 您感到惊讶, 因为您期望陡坡坡坡道的块速度更快, 并先到达底部。

    Sketch of two ramps with blocks showing varying steepness and ramp surfaces.

    Q: What explains your result?
    ::问题:什么解释你的结果?

    A: The block on the steeper ramp would have reached the bottom sooner if all else was equal. The problem is that all else was not equal. The ramps varied not only in steepness but also in smoothness. The block on the smoother ramp went faster than the block on the rougher ramp, even though the rougher ramp was steeper.
    ::甲:如果其他都一样的话,陡坡坡道上的块块会更快地到达底部。 问题在于其他所有坡道都不一样。 坡道不仅在陡坡上,而且在平滑上也各不相同。 滑坡坡坡道上的块块比粗坡坡道上的块块要快, 尽管粗坡坡道更陡。

    This example illustrates another important aspect of experiments: controlled variables . A controlled variable is a variable that is intentionally kept constant so it won’t influence the outcome of an experiment. By controlling any variables that could have an effect on the results of an experiment, we can  be confident that the manipulated variable is responsible for our results. In the case of your ramp experiment, smoothness of the ramps should have been controlled by making each ramp out of the same material. For other examples of controlled variables in an experiment, watch the video below. It is Part II of the above video on bouncing balls.
    ::这个示例展示了实验的另一个重要方面: 受控变量。 受控变量是一个变量, 它有意保持恒定, 从而不会影响实验的结果。 通过控制任何可能对实验结果产生影响的变量, 我们可以确信被操纵变量对我们的结果负有责任。 在你的斜坡实验中, 斜坡的平滑性应该通过从同一材料中做出一个斜坡来控制。 对于实验中其他受控变量的例子, 请看下面的视频。 这是上面关于弹簧球的视频的第二部分 。

     

     

    Q: What other variables do you think might influence the outcome of your ramp experiment? How could these other variables be controlled?
    ::问题:你认为还有什么其他变量会影响您的斜坡实验结果?如何控制这些变量?

    A: Other variables might include variables relating to the block. For example, a smoother block would be expected to go down a ramp faster than a rougher block. You could control variables relating to the block by using two identical blocks.
    ::A: 其它变量可能包括与块有关的变量。 例如, 平滑的块会以比粗糙块更快的速度下坡。 您可以使用两个相同的块来控制与块有关的变量 。

    Summary
    ::摘要

    • An experiment is a controlled scientific study of specific variables. A variable is a factor that can take on different values.
      ::实验是对特定变量的受控科学研究。变量是一个可以吸收不同值的因素。
    • There must be at least two variables in any experiment: a manipulated variable and a responding variable.
      ::在任何实验中必须至少有两个变量:一个被操纵变量和一个响应变量。
    • A control is a variable that must be held constant so it won’t influence the outcome of an experiment.
      ::控制是一个变量,必须保持固定不变,这样它就不会影响实验的结果。

    Review
    ::回顾

    1. What is an experiment?
      ::什么是实验?
    2. Distinguish between the manipulated variable and the responding variable in an experiment.
      ::区分实验中被操纵的变量和响应的变量。
    3. Why is it important for other variables in an experiment to be controlled?
      ::为什么实验中的其他变量必须受到控制?