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一、填空题:1.浮力产生的原因是______,它的方向总是_的.2.物体的浮沉决定于_______和______.设物体重力为G,浮力大小为F,则①当F-G>0时,物体_______;②当F-G=0时,物体_;③当F-G<0时,物体_;物体漂浮在液面上的条件是_.若浸没在液体中的物体是实心的,则有p物_P液,物体就下沉;p物_P液,物体悬浮;P物_____P液,物体上浮.3.潜水艇的下潜和上浮是靠改变_来实现的;而气N球的上升和下降是靠改变______来实现的.
First, fill in the blank questions: 1. The buoyancy is caused by ______, its direction is always _. 2. The float of the object is determined by _______ and ______. Let the gravity of the object be G, the buoyancy is F, then 1 When FG> 0, the object _______; 2 When FG = 0, the object _; 3 When FG <0, the object _; The condition of the object floating on the liquid surface is _. If the object immersed in the liquid is solid ,P _P fluid, the object sinks; p _P fluid, the object is suspended; P _____P fluid, the object floats. 3. The submarine’s dive and float is achieved by changing _; The rise and fall of the gas N ball is achieved by changing ______.