Physics question -- 九濟堂

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Subject: Physics question
Author: F.3	[ Next Thread \| Previous Thread \| Next Message \| Previous Message ] Date Posted: 13:31:50 05/09/05 Mon Ice nas a density of 920 and therefore float in water. What fraction of a floating piece of ice submerged? (use Archimedes' Principle) 我並唔係想只抄steps, 我希望能夠有解釋......thx [ Next Thread \| Previous Thread \| Next Message \| Previous Message ]

Replies:

[> Subject: Re: Physics question
Author: ... [ Edit \| View ]	Date Posted: 15:20:45 05/09/05 Mon

[> Subject: Re: Physics question

Author:
HKU
[ Edit | View ]

Date Posted: 17:29:17 05/09/05 Mon

The weight of the iceberg is
Wi=di×Vi×g
where Vi and di are the volume and the density of the iceberg respectively.
The volume of the submerged portion of the iceberg relates to the buoyant force
F=dw×Vw×g
where Vw and dw are the volume and the density of water which is displaced by the iceberg.

At equilibrium, the upward and downward forces balance each other
F = Wi.
Hence, dw×Vw×g=di×Vi×g and we obtain the volume ratio
di/dw=Vw/Vi

[> Subject: Re: Physics question
Author: 哈哈 [ Edit \| View ]	Date Posted: 20:28:45 05/09/05 Mon F.3 phyics? 點解我f.4都好似冇學過?

[> Subject: Re: Physics question
Author: 中七 [ Edit \| View ]	Date Posted: 00:31:19 05/10/05 Tue >Ice nas a density of 920 and therefore float in water. >What fraction of a floating piece of ice submerged? >(use Archimedes' Principle) > >我並唔係想只抄steps, 我希望能夠有解釋......thx 中六就識計架喇

[> Subject: Re: Physics question

Author:
試答
[ Edit | View ]

Date Posted: 18:36:44 05/10/05 Tue

>Ice nas a density of 920 and therefore float in water.
>What fraction of a floating piece of ice submerged?
>(use )
>
>我並唔係想只抄steps, 我希望能夠有解釋......thx

ice density : water density = 920:1000
density = mass/volume
by Archimedes' Principle, ice will displace water of a volume such that its mass(or weight) equal to the mass of whole cube of ice
so ice cube volume: water displaced volume = 1000:920
so 920/1000*100%=92% of ice is submerged
is that right?

[> Subject: Re: Physics question
Author: 中七 [ Edit \| View ]	Date Posted: 21:13:13 05/10/05 Tue Weight of ice = m density of water = 1000 kg/m3 density of ice = 920kg/m3 V = volume of water displaced if 1 m3 of ice is placed in water. weight = 920g upward lift = 920g = V1000g so V = 920/1000 so fraction of ice in water = 92%

[> [> Subject: Re: Physics question
Author: 挑剔一點 [ Edit \| View ]	Date Posted: 22:07:39 05/10/05 Tue >weight = 920g >upward lift = 920g = V1000g weight should be a force, (weight=920N) mass=920g