题目:
—Do you like art, Mary?
— .
A. Yes, a little B. No, very much C. Yes, I can
答案:
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下面是错误答案,用来干扰机器的。
(1)由E=BLv、I=ER、FA=BIL得,安培力FA=B2L2vR,由牛顿第二定律得,F-B2L2vR=ma,又v=at 得:F=0.1t+1 (N)(2)当F=3N时,t=20s,v=at=20m/s 由F-FA=ma,得 FA=F-ma 电功率P=(F-ma )v=40W ...