流速仪测流速的原理是什么？
参考答案：
流速仪（旋杯或旋桨式）是用来测定水流中任意指定点的水流平均流速的仪器。它是由感应水流的旋转器（旋杯或旋桨），记录信号的记数器和保持仪器正对水流的尾翼等三部分组成。旋杯或旋桨受水流冲动而旋转，流速愈大，转速愈快。按每秒转数与流速的关系，便可推算出测点的流速，每秒转数n与流速V的关系，在流速仪鉴定槽中通过实验确定。每部流速仪出厂时都附有检定后的流速公式，为（K为仪器的检定常数，C为机器摩阻系数）
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| Dear Classmates, As young people, we don't always want to think about the past. 1 we often hear our grandfathers and grandmothers talk about cultural relics. They say we 2 protect some of these relics because they are important to our culture. 3 also say that these relics are important to us because they help us remember the 4 of our ancestors and respect what they have done. I'm sure you will 5 . After all, someday we will be 6 ourselves and will want our own children to protect them. So I have a plan for 7 the painting in the old temple, which is a fine cultural relic 8 in our hometown. It should be protected because it was painted by a 9 artist of the early Qing Dynasty. My plan is to get students to take a 10 to see it on a Saturday next month and then 11 some important people to join us. 12 , we can also write 13 about it for the town newspaper. Later, when others begin to 14 their help, perhaps we can 15 enough money to help the museum buy it. If you like my plan, please give me a note to your teacher. Thank you. | ||||
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