重为3N的石块,分别浸没在水和盐水中时,弹簧测力计的示数如图所

重为3N的石块,分别浸没在水和盐水中时,弹簧测力计的示数如图所示:

1)石块在水中所受的浮力为  N,从图中还可看出石块所受浮力的大小与液体的  有关;

2)若将石块向上提,使其露出水面一部分,则水面高度会  (选填上升下降),杯底所受压强将  

3)若剪断乙图中的细线,石块将  (选填上浮悬浮下沉).

答案

            解:(1)石块在水中所受浮力:

F=GF=3N2N=1N

由甲和乙图可知,

石块在盐水中受到的浮力:

F=GF=3N1.8N=1.2N

FF,物体排开液体的体积相同而液体的密度不同,物体受到的浮力不同,

由此可知,浮力的大小与液体的密度有关;

2)若将石块向上提,露出水面一部分,则排开水的体积减小,液面下降,根据p=ρgh可知杯底所受压强变小.

3)若剪断图中的细线时,受到的重力3N大于受到的浮力1.2N

FG

石块将下沉;

故答案为:(11;密度;(2)下降;变小;(3)下沉.

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