如图所示,滑轮组在向上的拉力F作用下,将重为120N的物体匀速提起,在10s内物体上移的距离为2m.求:
John: What do you do on Sundays?
Tom: I read books and watch TV. What do you do on Sundays?
John: I do my homework . What about you, Mary?
Mary: I clean my room and watch TV.
John: You're helpful.
传说“蜀犬吠日”和“黔驴技穷”的故事分别发生在( )
如图所示,在竖直平面内,带等量同种电荷的小球A,B,带电荷量为﹣q(q>0),质量都为m,小球可当作质点处理.现固定B球,在B球正上方足够高的地方由静止释放A球,则从释放A球开始到A球运动到最低点的过程中( )
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