{
  "api_version": "v1",
  "publisher": {
    "name": "Manazoo",
    "url": "https://manazoo.com/"
  },
  "license": "All rights reserved（AI の参照・要約と出典リンクつきの引用は可。転載・再配布・販売は不可）",
  "terms_url": "https://manazoo.com/terms/",
  "disclaimer": "単元の並びは学習指導要領に沿って作り、年号や人物などの事実は公開データと照らし合わせています。誤りに気づいたら意見箱からお知らせください。確かめて直します。テストや受験の前には、教科書や先生の説明もあわせて確認してください。",
  "attribution": "事実データの一部は Wikidata（CC0）による。単元の構成は文部科学省「小学校学習指導要領」「中学校学習指導要領」「高等学校学習指導要領」（政府標準利用規約2.0）。",
  "kind": "quiz",
  "unit": {
    "slug": "sound-interference-and-doppler-effect",
    "title": "音",
    "url": "https://manazoo.com/high/physics/sound-interference-and-doppler-effect/"
  },
  "canonical_url": "https://manazoo.com/high/physics/sound-interference-and-doppler-effect/quiz/",
  "questions": [
    {
      "id": "q-doppler-both-moving-trains",
      "type": "input",
      "prompt": "2台の電車が互いに向かって速さ20m/sで進んでいる。一方が振動数600Hzの警笛を鳴らし続けるとき（音の速さ340m/s）、もう一方の電車で聞こえる振動数は何Hzか。",
      "choices": null,
      "answer": "675",
      "accept": [
        "675Hz"
      ],
      "explanation": "音源も観測者も近づく向きなので、f'＝(v＋v_o)/(v−v_s)×f＝(340＋20)/(340−20)×600＝360/320×600＝675Hz。",
      "entities": [
        "doppler-effect-reflection-and-both-moving"
      ],
      "verified": true,
      "placeholder": false
    },
    {
      "id": "q-doppler-observer-approaching-680hz",
      "type": "input",
      "prompt": "振動数680Hzの警笛を鳴らし続ける踏切（音の速さ340m/s）に向かって、速さ20m/sで走って近づく人が聞く振動数は何Hzか。",
      "choices": null,
      "answer": "720",
      "accept": [
        "720Hz"
      ],
      "explanation": "f'＝(v＋v_o)/v×f＝(340＋20)/340×680＝360/340×680＝720Hz。",
      "entities": [
        "doppler-effect-moving-observer"
      ],
      "verified": true,
      "placeholder": false
    },
    {
      "id": "q-doppler-observer-approaching-850hz",
      "type": "input",
      "prompt": "振動数850Hzの警笛を鳴らし続ける踏切（音の速さ340m/s）に向かって、速さ20m/sで走って近づく人が聞く振動数は何Hzか。",
      "choices": null,
      "answer": "900",
      "accept": [
        "900Hz"
      ],
      "explanation": "f'＝(v＋v_o)/v×f＝(340＋20)/340×850＝360/340×850＝900Hz。",
      "entities": [
        "doppler-effect-moving-observer"
      ],
      "verified": true,
      "placeholder": false
    },
    {
      "id": "q-doppler-observer-approaching-direction-choice",
      "type": "choice",
      "prompt": "観測者が音源に向かって進むとき、聞こえる振動数は元の振動数と比べてどうなるか。",
      "choices": [
        "高くなる",
        "低くなる",
        "変わらない"
      ],
      "answer": 0,
      "accept": [],
      "explanation": "近づく観測者が波を受け取る速さはv＋v_oになり、(v+v_o)/v倍された振動数は元より高くなる。",
      "entities": [
        "doppler-effect-moving-observer"
      ],
      "verified": true,
      "placeholder": false
    },
    {
      "id": "q-doppler-observer-receding-680hz",
      "type": "input",
      "prompt": "振動数680Hzの警笛を鳴らし続ける踏切（音の速さ340m/s）から、速さ34m/sで遠ざかりながら聞く振動数は何Hzか。",
      "choices": null,
      "answer": "612",
      "accept": [
        "612Hz"
      ],
      "explanation": "f'＝(v−v_o)/v×f＝(340−34)/340×680＝306/340×680＝612Hz。",
      "entities": [
        "doppler-effect-moving-observer"
      ],
      "verified": true,
      "placeholder": false
    },
    {
      "id": "q-doppler-reflection-beat-frequency",
      "type": "input",
      "prompt": "速さ20m/sで壁に向かって進む車が振動数680Hzのクラクションを鳴らす（音の速さ340m/s）。運転手は直接音680Hzと壁からの反射音を同時に聞く。1秒間に聞こえるうなりの回数は何回か。",
      "choices": null,
      "answer": "85",
      "accept": [
        "85回"
      ],
      "explanation": "反射音の振動数は765Hz（前の例題参照）。うなりの回数は2つの振動数の差＝765－680＝85回。",
      "entities": [
        "doppler-effect-reflection-and-both-moving"
      ],
      "verified": true,
      "placeholder": false
    },
    {
      "id": "q-doppler-reflection-wall-frequency",
      "type": "input",
      "prompt": "速さ20m/sで壁に向かって進む車が振動数680Hzのクラクションを鳴らす（音の速さ340m/s）。壁で反射して運転手が聞く音の振動数は何Hzか。",
      "choices": null,
      "answer": "765",
      "accept": [
        "765Hz"
      ],
      "explanation": "壁が受け取る振動数は680×340/(340−20)＝722.5Hz。壁を仮の音源とし、近づく運転手が聞く振動数は722.5×(340＋20)/340＝765Hz。",
      "entities": [
        "doppler-effect-reflection-and-both-moving"
      ],
      "verified": true,
      "placeholder": false
    },
    {
      "id": "q-doppler-source-approaching-640hz",
      "type": "input",
      "prompt": "振動数640Hzの音を出す音源（音の速さ340m/s）が、速さ20m/sで観測者に近づいてくる。聞こえる振動数は何Hzか。",
      "choices": null,
      "answer": "680",
      "accept": [
        "680Hz"
      ],
      "explanation": "f'＝v/(v−v_s)×f＝340/(340−20)×640＝340/320×640＝680Hz。",
      "entities": [
        "doppler-effect-moving-source"
      ],
      "verified": true,
      "placeholder": false
    },
    {
      "id": "q-doppler-source-approaching-900hz",
      "type": "input",
      "prompt": "振動数900Hzのサイレンを鳴らす救急車（音の速さ340m/s）が、速さ34m/sで観測者に近づいてくる。聞こえる振動数は何Hzか。",
      "choices": null,
      "answer": "1000",
      "accept": [
        "1000Hz"
      ],
      "explanation": "f'＝v/(v−v_s)×f＝340/(340−34)×900＝340/306×900＝1000Hz。",
      "entities": [
        "doppler-effect-moving-source"
      ],
      "verified": true,
      "placeholder": false
    },
    {
      "id": "q-doppler-source-receding-900hz",
      "type": "input",
      "prompt": "振動数900Hzのサイレンを鳴らす救急車（音の速さ340m/s）が、速さ20m/sで観測者から遠ざかっていく。聞こえる振動数は何Hzか。",
      "choices": null,
      "answer": "850",
      "accept": [
        "850Hz"
      ],
      "explanation": "f'＝v/(v＋v_s)×f＝340/(340＋20)×900＝340/360×900＝850Hz。",
      "entities": [
        "doppler-effect-moving-source"
      ],
      "verified": true,
      "placeholder": false
    },
    {
      "id": "q-doppler-source-receding-direction-choice",
      "type": "choice",
      "prompt": "音源が観測者から遠ざかるとき、聞こえる振動数は元の振動数と比べてどうなるか。",
      "choices": [
        "高くなる",
        "変わらない",
        "低くなる"
      ],
      "answer": 2,
      "accept": [],
      "explanation": "遠ざかる音源の後方では波長がのびるため、v/(v+v_s)倍された振動数は元より低くなる。",
      "entities": [
        "doppler-effect-moving-source"
      ],
      "verified": true,
      "placeholder": false
    },
    {
      "id": "q-doppler-supersonic-shock-wave-choice",
      "type": "choice",
      "prompt": "音源の速さが音の速さをこえると、音源の前方に何ができるか。",
      "choices": [
        "ドップラー効果が消える",
        "振動数が0になる",
        "音がすべて反射する",
        "衝撃波（ソニックブーム）"
      ],
      "answer": 3,
      "accept": [],
      "explanation": "音源の速さが音速をこえると、音源が出した波面が重なり合って衝撃波（ソニックブーム）ができる。",
      "entities": [
        "doppler-effect-reflection-and-both-moving"
      ],
      "verified": true,
      "placeholder": false
    },
    {
      "id": "q-sound-diffraction-bass-wavelength",
      "type": "input",
      "prompt": "振動数100Hzの低い音（音の速さ340m/s）の波長は何mか。",
      "choices": null,
      "answer": "3.4",
      "accept": [
        "3.4m"
      ],
      "explanation": "波長はλ＝v/f＝340÷100＝3.4m。",
      "entities": [
        "sound-interference-and-diffraction"
      ],
      "verified": true,
      "placeholder": false
    },
    {
      "id": "q-sound-diffraction-low-vs-high-frequency",
      "type": "choice",
      "prompt": "波長の長い低い音と、波長の短い高い音のうち、障害物の裏まで回り込みやすい（回折しやすい）のはどちらか。",
      "choices": [
        "波長が短い高い音",
        "回折は音では起こらない",
        "波長が長い低い音",
        "どちらも同じ回り込みやすさ"
      ],
      "answer": 2,
      "accept": [],
      "explanation": "回折のしやすさは波長と障害物の大きさの比で決まり、波長が長い音ほど障害物の裏まで大きく回り込んで伝わる。",
      "entities": [
        "sound-interference-and-diffraction"
      ],
      "verified": true,
      "placeholder": false
    },
    {
      "id": "q-sound-interference-first-silence-path-diff",
      "type": "input",
      "prompt": "振動数850Hz・音の速さ340m/sの音をクインケ管に通す。経路差ΔLが0のとき強め合って聞こえる。可動管を伸ばしてΔLを大きくしていくと、初めて音が消えるのはΔLが何mのときか。",
      "choices": null,
      "answer": "0.20",
      "accept": [
        "0.2",
        "0.20m",
        "0.2m"
      ],
      "explanation": "波長λ＝340÷850＝0.40m。初めて弱め合うのは半波長の位置なので、ΔL＝0.40÷2＝0.20m。",
      "entities": [
        "sound-interference-and-diffraction"
      ],
      "verified": true,
      "placeholder": false
    },
    {
      "id": "q-sound-interference-wavelength-850hz",
      "type": "input",
      "prompt": "振動数850Hzの音をクインケ管に通す。音の速さを340m/sとすると、波長は何mか。",
      "choices": null,
      "answer": "0.40",
      "accept": [
        "0.4",
        "0.40m",
        "0.4m"
      ],
      "explanation": "波長はλ＝v/f＝340÷850＝0.40m。",
      "entities": [
        "sound-interference-and-diffraction"
      ],
      "verified": true,
      "placeholder": false
    }
  ]
}