3 |
4 |
1 |
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∵物体漂浮时受到的浮力和自身的重力相等,
∴根据F浮=ρgV排和ρ=
m |
V |
F浮=ρ水gV排=m泡沫g,即ρ水g×
1 |
4 |
解得:ρ泡沫=
1 |
4 |
把细线剪断前,泡沫球和塑料球漂浮,则
F浮′=ρ水gV排′=(m泡沫+m塑料)g,即ρ水g(V塑料+
1 |
2 |
∵V塑料:V泡沫=1:8,
∴ρ水(V塑料+
1 |
2 |
1 |
4 |
整理可得:ρ塑料=3ρ水=3×1×103kg/m3=3×103kg/m3.
故答案为:3×103.
3 |
4 |
3 |
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1 |
4 |
m |
V |
1 |
4 |
1 |
4 |
1 |
2 |
1 |
2 |
1 |
4 |