Yahoo 知識+ 將於 2021 年 5 月 4 日 (美國東岸時間) 停止服務。從 2021 年 4 月 20 日 (美國東岸時間) 起,Yahoo 知識+ 網站將轉為僅限瀏覽模式。其他 Yahoo 資產或服務,或你的 Yahoo 帳戶將不會有任何變更。你可以在此服務中心網頁進一步了解 Yahoo 知識+ 停止服務的事宜,以及了解如何下載你的資料。

Urgent ! Physics , 高人請指教 !

A block of melting ice with mass 0.02 kg is put into a polystyrene cup containing 0.3 kg

of water with initial temperature 20 ''C . After the mixture is stirring well , the ice block melt completely and the final temperature of the water becomes 14 ''C .Which of the following is to find the latent heat of fusion of ice, L ?

0.3x4200x6 =0.02L

0.3x4200x6 =0.02L - 0.02x4200x6

0.3x4200x6 =0.02L+ 0.02x4200x6

0.3x4200x6 =(0.02L+ 0.02x4200)x14

0.3x4200x6 =0.02L+ 0.02x4200x14

2 個解答

  • 1 十年前

    energy is transferred from the 20 deg 0.3kg water to melt the 0.02kg ice and raise the temperature of the 0 deg 0.02kg water to 14 deg

    (input) energy offered by the 0.3kg water=(0.3x4200x6)J

    (output 1) energy absorbed to melt 0.02kg ice=(0.02L)J

    (output 2) energy absorbed to raise the temperature by 14deg=0.02x4200x14

    by conservatin of energy, 0.3x4200x6 =0.02L+ 0.02x4200x14

    資料來源: myself
  • 1 十年前

    By conservation of energy

    energy to melt 0.02kg of ice+energy required to raise 0.02 kg of water at 0 度to 14度=energy released by 0.3kg from 20度 to 14度raise

    m1 *Lv=m1*c *delta T=m2 *c *delta T

    0.02L+ 0.02x4200x14= 0.3x4200x6