1、上上浮力浮力液体或气体液体或气体竖直向上竖直向上GF压力差压力差F向上向上F向下向下体积体积密度密度体积体积密度密度大大重力重力G排排液液V排排g =等于等于相同相同增大增大空心空心排水量排水量小于小于不变不变重力重力大于大于0.50.5竖直向上竖直向上0.40.4不变不变A AB B物体排开液体的体积物体排开液体的体积丙丁丙丁4 44 41010-4-41.11.110103 3解:解:(1 1)石块的重力)石块的重力G=mg=0.78G=mg=0.78KgKg10N/Kg=7.8N10N/Kg=7.8N 浮力浮力F F浮浮=G-F=7.8N-4.2N=3.6N=G-F=7.8N-4.2N=
2、3.6N(2)石块的体积石块的体积V=V=V排排=F F浮浮/液液g =3.6N/(1.03.6N/(1.010103 3Kg/mKg/m3 310N/Kg)10N/Kg)=3.63.610-10-3 3m m3 3 石块的密度石块的密度=m/V=0.78m/V=0.78Kg/Kg/3.63.610-10-3 3m m3 3=2.2=2.210103 3Kg/mKg/m3 3(3 3)水位下降的高度)水位下降的高度hh=V/S=3.6=V/S=3.610-10-3 3m m3 3/(180/(1801010-4-4m m2 2)=0.02m)=0.02m 2020增大增大下沉下沉8.88.81
3、0103 32 2A AD D解:解:(1 1)木块的浮力)木块的浮力F F浮浮=G=G排排=m=m排排g=0.6g=0.6KgKg10N/Kg=6.0N10N/Kg=6.0N (3)(3)正方体木块的边长正方体木块的边长a=0.1ma=0.1m,面积,面积S=0.01S=0.01m m2 2 木块的下表面所受水的压力木块的下表面所受水的压力F=F F浮浮=6.0N=6.0N 木块的下表面所受水的压强木块的下表面所受水的压强P=F/S=P=F/S=6.0N6.0N/0.01/0.01m m2 2=600Pa=600Pa (2)木块漂浮,木块漂浮,F F浮浮=G=G木木=6.0N=6.0N 木块的体积木块的体积V V=G G木木/木木g=6.0N/(0.6.0N/(0.610103 3Kg/mKg/m3 310N/Kg)10N/Kg)=1 110-10-3 3m m3 3=D DD DD D303060602 2C C