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题1 一条细线穿过光滑水平板上的小孔,一端拴小球A,另一端连接砝码B,B的下端再连接一砝码C,现小球A正在水平板上做匀速圆周运动,如图1所示.如果将连接B 和C的细绳烧断,则小球A在新的轨道上做匀速圆周运动时,它的轨道半径r、角速度ω、线速度v 的大小变化情况是( ) (A)r增大,v不变. (B)ω不变,r减小. (C)r增大,v减小. (D)r不变,v减小. 分析将连接B和C的细绳烧断时,A受到的拉力不足以提供它做圆周运动的向心力,所以A做离心运动,轨道半径r变大,砝码B上升.
Question 1 A thin line passes through a small hole in the smooth horizontal plate. One end is ball A, and the other end is connected to the weight B. The lower end of B is connected with a weight C. The ball A is making a uniform circular motion on the horizontal plate. As shown in Fig.1, if the string connecting B and C is blown, the size of its orbital radius r, angular velocity ω, and linear velocity v change when the ball A makes a uniform circular motion on the new orbit. Yes () (A) r increases, v does not change. (B) ω does not change, r decreases. (C) r increases, v decreases. (D) r does not change, v decreases. Analysis will connect When B and C’s string is blown, A’s pulling force is not enough to provide the centripetal force of its circular motion. So A does centrifugal motion, the orbital radius r becomes larger, and the weight B rises.