问题
选择题
在河水中游泳的人沿鹅卵石河床由深水走向浅水的过程中感到脚底越来越痛是因为（ ）
A．人所受的浮力越来越小
B．人所受的浮力越来越大
C．人所受的重力越来越大
D．人所受的重力越来越小
答案
人在水中由深水走向浅水时，人的质量不变，则重力没有变化；由于人排开水的体积减小，根据阿基米德原理F浮=ρ液gV可知：人所受浮力减小．
故选D．
搜题请搜索小程序“爱下问搜题”
在河水中游泳的人沿鹅卵石河床由深水走向浅水的过程中感到脚底越来越痛是因为（ ）
A．人所受的浮力越来越小
B．人所受的浮力越来越大
C．人所受的重力越来越大
D．人所受的重力越来越小
人在水中由深水走向浅水时，人的质量不变，则重力没有变化；由于人排开水的体积减小，根据阿基米德原理F浮=ρ液gV可知：人所受浮力减小．
故选D．
More Than I Had Dreamed Of From the time I was seven, I had a dream of becoming a member of the Students Union．I always 36 my school leaders for taking responsibility for all of us．So I dreamed of being a leader． Years flew by, and soon I was able to participate in the elections, 37 I would win．But the reality struck that I hadn't had a chance．I wasn't pretty．Girls across the school hardly knew me．I just did not have what it 38 to win a school election．I was 39 ． As I cried in my room that evening, I 40 took a deep breath and decided I wouldn't stop dreaming．I decided that I would 41 for elections again in my final year at school—and I would win． I recognized that my 42 had a lot of things in their favor．What were the 43 that would work in my favor? I had good grades, and I was friendly and helpful．And my biggest 44 was the faith I had．I would not allow my 45 appearance to hold me back from putting my best foot forward．That evening, I 46 my election plans a whole year in advance． I realized that girls would have to get to know me and recognize that I had the ability to 47 them．I loved making friends and I liked being helpful, 48 I decided that perhaps I could use these qualities to work to my advantage．In order to learn how to present a great election 49 , I also attended a course on effective public speaking． The day after the election, when the principal announced I won the second highest number of votes, the students 50 That joy on the faces of all my friends showed me that my victory was 51 theirs． Suddenly, I realized that I had 52 much more than I had dreamed of．I had made many new friends and had helped people 53 the way．I had won the 54 and love of my school-mates and they knew me as somebody who would stand by them．I was able to put a smile on their faces and 55 their day．
|