1.某杠杆的动力臂是阻力臂的5倍,阻力为200牛,则杠杆平衡时,动力为_______牛;若另一杠杆的阻力臂是动力臂的5倍.阻力仍为200牛,则杠杆平衡时,动力为_______牛.
2.若杠杆左端偏高,那么左端螺母应向_______调节,使杠杆在__________(选填"左端"或"右端")平衡.
3.OA是轻制杠杆,已知OB=2AB,B点所挂物体的重力为6牛,A端用力F竖直向上拉着,杠杆处于静止状态,则力F的大小为_____牛.当力F向左倾斜时,为使杠杆仍保持静止,则力F的大小需_______(选填"增大"."不变"或"减小").
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