Question

用不等臂的天平稱物體的質(zhì)量，物體放在右盤時，稱得質(zhì)量為m₁；放在左盤時，稱得質(zhì)量為m₂.則物體質(zhì)量是

A.                                                           B.

C.                                                             D.

Answer 1

解析：如圖4-4-1所示，設(shè)不等臂天平的兩臂分別為l₁、l₂，被測物體的質(zhì)量為m.天平平衡時，根據(jù)力矩平衡條件，當(dāng)物體放在右盤時有

m₁gl₁-mgl₂＝0                                                                                                                ①

當(dāng)物體放在左盤時有mgl₁-m₂gl₂＝0                                                                         ②

由①②解得

m=，應(yīng)選C.

答案:C