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物理 高校生

(5)の単振動、最大の速さについての質問です!解説は理解出来てますが、2枚目にあるように単振動の位置エネルギーで表せないのはなぜですか?

114 力学 38 単振動 水平面内において一定の角速度ので 回転している円板がある。 円板上には, 半径方向にみぞが掘られており、その中 にばね定数k,自然長のばねが置かれ ている。 ばねの一端は中心0に固定され, 他端には質量Mの小球Pがつけられてい る。 Pはみぞの中を滑らかに動け, 0 か つ らPまでの距離rを用いておもりの位置を表す。 いま、円板上で静止 している観測者Aには, Por=ro の点に静止して見えた。 真上から見た図 Level (1), (2)★ (3)~(5)★ Point & Hint W (1) ro をlk, M, ω を用いて表せ。 (2) こうなるために必要な角速度に対する条件を表せ。 次に,Pをみぞに沿って外側に動かし, 点0 からの距離 n の点で静 かにPを放したところ, P はみぞの中で運動を始めた。 (3) Pが位置にあるときAが見る加速度をaとすると, A が書くべ き運動方程式はどのようになるか。 みぞ方向外向きを正とする。 (4) Pの位置を,rの代わりに ro から測ってx=r-ro を用いて表 すと, 運動方程式の右辺の力はLx の形になる。 Lをk, M, ω を 用いて表せ。 (5) Pを放してからばねの長さが最小となるまでの時間, ばねの長さ の最小値,およびAが見るPの最大の速さをk, M, w, ro, n, のう ち必要なものを用いて表せ。 (北海道大) Aにとっては遠心力が現れている。 (2) (1) の答えの形から自然に条件が決まってくる。 (5) (4) の結果からPの運動が確定する。 P the p LECTURE (1) 遠心力と弾性力のつり合いより Mrow²=k(ro-l ... (2)>0より kl Yo= k-Mw² k-Mw² > 0 k w√ M 回転が速過ぎると(ωが大き過ぎると),弾 性力より遠心力がまさり つり合う位置がな くなってしまう。 (3) ばねの伸びは -l と表せるから Ma=Mrw²-k(r-1) (4) 上式に r = ro+x を代入すると ( 38 単振動 •mmmm 自然長 遠心力がかかるから, | ばねは伸びているはず。 ①を用いた 115 遠心力 Mをmと書いてい ないだろうか? 物体上から見たとき 向心 外から見たとき ▷じゃ Ma = M(ro+x)w² − k(ro+x-1) ) =Mxw²2-kx =-(k-Mω²)x ......2 ∴. L=k-Mo² (2)で求めた条件よりLは正の定数であり,②はPがx=0(力のつり合 い位置)を中心として単振動をすることを示している。 (5) ②から単振動の周期Tは M 最大の速さは、 公式 Vmax = Aw より [ro を代入する) より速い Queeeeeeeeeeee- 0 Yo T=2nvk-M²2 2π√ とする誤りが多い。ばね振り子の周期 k が不変となるのは、ばねの力のほかに一定の力 がかかる場合のことである。 遠心力は半径と ともに変わる力である。 ばねの長さが最小となるのは, 内側の端の位置にくるときだから、端か ら端までの時間は半周期。よって, M T= √k-M₁² 振幅Aは上図より, A = n-ro よって, ばねの長さの最小値は ro-A=2ro-n # A 中心 k-Mos² A² = (n-1)√² M

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英語 高校生

答えに解説がなくて困ってます。 下の長文を翻訳してください。

〔Ⅰ〕 次の英文を読み. 設問 1~21 に答えよ。 Sandy lives in an apartment so small that when she comes home from shopping, she has to decide what to move out to make room for her purchases. She struggles day-to-day to feed and clothe herself and her four-year-old daughter on money from freelance writing jobs and helping neighbors. (2) Her ex-husband has long since disappeared down some unknown highway, probably never to be heard from again. As often as not, her car decides it needs a day off and refuses to start. That means bicycling (weather permitting), walking or asking friends for a ride. 13 The things most Americans consider essential for survival- a television. microwave, big freezer and high-priced sneakers are far down Sandy's list of "maybe someday" items. (5) Nutritious food, warm clothing, an affordable apartment, student loan payments, books for her daughter, absolutely necessary medical care and an occasional movie eat up what little money there is to go around. Sandy has knocked ) more doors than she can recall, trying to find (7) a decent job, but there is always something that doesn't quite fit-too little experience or not the right kind, or hours that make child care impossible. Sandy's story is not unusual. Many single parents and older people struggle with our economic structure, falling into the gap between being truly self-sufficient and being poor enough that the government will provide assistance. What makes Sandy unusual is her outlook. "I don't have much in the way of stuff or the American dream," she told me with a genuine smile. "Does that bother you?" I asked. "Sometimes. When I see another little girl around my daughter's age who has nice clothes and toys, or who is riding around in a fancy car or living in a fine house, then I feel bad. Everyone wants to do well for their children." she replied. "But you're not angry?" "What's to be angry (9) and I have what is really important in life," she replied. "And what is that?" I asked. (10) "As I see it, no matter how much stuff you buy, no matter how much )? We aren't starving or freezing to death. (11) money you make. you really only get to keep three things in life." she said. "What do you mean by 'keep?" (12) "I mean that nobody can take these things away from you." "And what are these three things?" I asked. "One, your experiences: two, your true friends; and three, what you grow inside yourself." she told me without hesitation. (13) For Sandy, "experiences" don't come on a grand scale. They are so-called ordinary moments with her daughter, walks in the woods, napping under a shady tree, listening to music, taking a warm bath or baking bread. Her definition of friends is more expansive. "True friends are the ones (15) who never leave your heart, even if they leave your life for a while. Even after years apart. you pick up with them right where you left off, and even if they die, they're never dead in your heart," she explained. 16 ) to each of us. (17 As for what we grow inside, Sandy said, "That's ( isn't it? I don't grow anger or sorrow. I could if I wanted to, but I'd rather not." "So what do you grow?" I asked. Sandy looked warmly at her daughter and then back to me. She pointed toward her own eyes, which were shining with tenderness. gratitude and a sparkling joy. "I grow this." From the book Chicken Soup for the Woman's Soul by Jack Canfield. Mark Victor Hansen. Jennifer Read Hawthorne, and Marci Shimoff. Copyright 2012 by Chicken Soup for the Soul Publishing, LLC. Published by Backlist. LLC. a unit of Chicken Soup for the Soul Publishing. LLC. Chicken Soup for the Soul is a registered trademark of Chicken Soup for the Soul Publishing, LLC. Reprinted by permission. All rights reserved.

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英語 高校生

英語の論理表現の問題です 大問4の4の並び替え問題についてです この問題のuselessの使い方について教えてほしいです!

3 ite! 2. 1. 3. 4. 4 15 6. 3. 次の英文を日本語に直しなさい。 1. ) dangerous ( 各文の下線部と同じ用法の不定詞を含む文を(a)~(d)から選びなさい。 I will go to the stadium to see a soccer game. (a) (b) I'm sorry to bother you, but there is a phone call for yo He can't be kind to other people to tell such a bad joke He made a promise to send me an email every day. We should leave soon to get there on time. There was nothing to eat in the refrigerator. My sister was looking for a company to work for You should grow up to be kind people. It is important to help each other. He had three children to look after. (c) (d) He went to the bookstore to buy the comic book. I want to be a nurse in the future. He tried, only to find he couldn't solve the problem by hir She needs a bigger house to live in. 4 ( 内の語句を並べかえて, 英文を完成させなさい。 1. I ( planning/ a three-day trip/to/am/to Kanazawa/take ). 2. Tony (the/speak/to/ability/three languages/has). X He must (to/ a mistake/tired/be/make/such). (useless/I/to/it/talk/think) to my mother about it. 5. (receive/were/to/a warm welcome/the tourists/delighte 6. Takashi (Canada/to/in/stayed/his/improve ) English. 総合 1. 彼女には洗わなければならない服がたくさんある。 2. 私は目が覚めたら部屋に一人ぼっちだった。

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