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暑假得闲,在拜读《物理教学》2006年第6期刊登的《强化构造意识,灵活应变策略》文章时,发现文中对有些物理习题的分析不够科学严密,解答中出现错误和瑕疵,下面就文中的几道例题分别指出。[例3]用粗细相同的钢丝做成半径分别为 R 和2R 的两只闭合圆环 A 和 B,如图1所示。现以相同的速度把两环从磁感强度为 B 的匀强磁场区域中匀速地拉到磁场外,不考虑圆环的动能,若外力对环所做的功分别为 W_A 和 W_B,则W_A:W_B 为( )。(A)1:4 (B)1:2 (C)1:1 (D)无法确定
I had a leisure time during the summer vacation. When I read the article “Strengthening Tectonic Consciousness, Flexible Response Strategies” published in the 6th issue of “Physics Education” in 2006, I found that the analysis of some physics exercises in the article was not scientific enough. There were mistakes and errors in the answers. A few examples were pointed out separately. [Example 3] Two closed loops A and B with R and 2R radii are made of steel wire of the same thickness as shown in Fig. 1 . At the same speed, the two rings are pulled from the uniform magnetic field with a magnetic induction strength B to the outside of the magnetic field at a uniform speed, regardless of the kinetic energy of the ring. If the work done by the external force on the ring is W_A and W_B, respectively, W_A : W_B is (). (A) 1:4 (B) 1:2 (C) 1:1 (D) Unsure