逋逋* 發問時間: 科學其他:科學 · 10 年前

物理波與波長頻率問題麻煩一下

1. if a pendulum clock is accurate at sea level, will it gain or lose time when taken to high altitude? why?

2. a small fly of mass 0.25g is caught in a spider's web. the web vibrates predominantly with a frequency of 4 HZ a)what is the value of the spring stiffness k for the web? b) at what frequency would you expect the web to vibrate if an inscet of mass 0.50g were trapped?

3.sketch a series of standing waves on a string between two sold points. show the first three harmonics.

1 個解答

評分
  • 小白
    Lv 7
    10 年前
    最佳解答

    1.

     

    lose time

     

    鐘擺週期 T = 2π√(l/g),當鐘擺被移至海拔較高處,則重力變小,即 g' < g,則 T' > T,鐘擺週期將變大,看起來像是擺動速度變慢,由於這種鐘是每擺動一次計時1秒,時間一久,此鐘顯示的時間將愈來愈落後在海平面的鐘。

     

    2.

     

    (a) 彈簧簡諧振盪週期 T = 2π√(m/k),亦即頻率 f = (1/2π)√(k/m),

     

    4 = (1/2π)√(k/0.00025) => k = 0.16 NT/kg

     

    (b) f ∝ 1/√m => f' = 4 × √(0.25/0.5) = 2.8 Hz

     

    3.

     

    駐波的前三倍頻如下圖的上三圖所示:

     

    圖片參考:http://www.phys.unsw.edu.au/jw/graphics/standing.G...

     

     

    參考資料:

    http://www.phys.unsw.edu.au/jw/strings.html

    http://phys.thu.edu.tw/teachers/lin/physics-ch08.p...

     

     

    2011-01-09 22:13:14 補充:

    k值的單位寫錯,應為0.16 NT/m。

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