题干

在学过摩擦力知识后,小明想探究:摩擦力大小是否与压力、重力都有关系?他利用如图所示的装置进行探究实验.

实验步骤如下:

①把金属盒放在质量不计的白纸上,读出台式测力计示数;拉动白纸的过程中,读出弹簧测力计的示数.

②将质量不计的氢气球系在金属盒上,读出台式测力计示数;拉动白纸的过程中,读出弹簧测力计的示数.

③再往金属盒注入适量的沙子,使台式测力计示数与步骤①中的示数相等,拉动白纸的过程中,读出弹簧测力计的示数.

实验相关数据如下表:

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    More than 2.25 billion cups of coffeeare consumed across the globe each day, and it's likely that many taste bitter.

    Now, a new study suggests that coffeefans can make their drink taste sweeter by simply changing the color of theircups.

Scientists claim that blue and glass mugs,which are popular in some coffee shops, can reduce coffee's bitterness, withoutany need for sugar, and that coffee drunk from white cups tastes the bitterest.

    To prove their claims, the researchersinvited 36 volunteers and used three different colored cups— blue, white andtransparent glass—to do an experiment.

    In the experiment, coffee consumed fromthe white cup was found to taste less sweet when compared to the other twocolored cups, while the blue cup made the coffee taste the sweetest.

    The scientists believe that the colorbrown may be associated with coffee's bitterness because coffee in a white cupappears the brownest and tastes the bitterest.

  “Our study clearly shows that the colorof a coffee cup does influence the perceived (感受到的) taste and flavor of coffee,” said DrGeorge Doorn of Federation University Australia, “but the potential effects maybe different between a one-time purchase and a return customer.”

  “Anyhow, the effect of the color of thecup on the flavor of the coffee suggests that café owners, baristas (服务员), aswell as coffee cup manufacturers should carefully consider the color of theircups, ” he added.

    However, the idea that color can alterthe taste of food and drink is not new.

    A study published last year revealedthat red, strawberry-flavored mousse (慕斯蛋糕) served on a white plate was rated as10 percent sweeter and 15 percent more flavorous than the same food presentedon a black plate.