Find the buoyant force on the iceberg

[ombudsmansect]

Homework Statement

A 6500-kg iceberg with density 931kg/m^3 is afloat in seawater with density 1030kg/m^3. a) Find the buoyant force on the iceberg b) the volume of water displaced by the iceberg c) The fraction of the icebergs volume that is below the waterline.

Homework Equations

Fb = pgV

V = (mg -Wa)/pg

The Attempt at a Solution

I have tried everything this is one of the hardest questions for this part. All solutions i have attempted end up equalling themselves or 1 or 0 or something u knw. I am guessing some sort of simultaneous equation setup is need or find the fraction of the Volume that is underwater first somehow but i just can't get there. If someone who has done this sort of prob bfore can tell me the secret ill b happy :D. CHeers.

 

[louza8]

i'll have a go

a) It says its afloat right? So therefore the buoyant force must be pushing up the entire weight of the iceberg. How much does the iceberg weigh?

b)volume of water displaced by the iceberg will equal the fraction of the iceberg's volume that is under the ocean. only some of the iceberg is under the sea and some is above. this fraction is determined by the densities: 931/1030. so now we know the fraction, we just multiply it by the volume of the iceberg (determined by density and mass of berg).

c) fraction below the water is as mentioned 931/1030 and hence fraction above the water will be 1 minus the above fraction.

sounds about right to me but I'm not willing to bet a testicle

 

[ombudsmansect]

nice one thanks for the reply. I didn't think anyone was game enough to give it a go lol. You are actually right for a) i didn't think that it would be the equivalent of the whole weight but it was! after that everything else falls into place. thanks heaps for ur help mate :D

 

[louza8]

no problemo I'm learning too so its fun when i can actually do problems lol

 

[rdl]

I would approach this problem by first reviewing the given information and identifying the relevant equations to use. From the homework statement, we can see that the problem involves an iceberg floating in seawater, so we can apply Archimedes' principle, which states that the buoyant force on an object in a fluid is equal to the weight of the fluid displaced by the object.

a) To find the buoyant force on the iceberg, we can use the equation Fb = pgV, where p is the density of the fluid (in this case, seawater), g is the acceleration due to gravity, and V is the volume of water displaced by the iceberg. We can calculate the volume of the iceberg using its density and mass, V = m/p, and then substitute this value into the equation to find the buoyant force.

b) The volume of water displaced by the iceberg is equal to its own volume, as stated by Archimedes' principle. So, we can use the same equation as in part a) to calculate this volume.

c) To find the fraction of the iceberg's volume that is below the waterline, we can use the equation V = (mg - Wa)/pg, where m is the mass of the iceberg, g is the acceleration due to gravity, p is the density of the fluid, and Wa is the weight of the iceberg. This equation gives us the volume of the iceberg that is submerged in the fluid, which we can then divide by the total volume of the iceberg to find the fraction.

In summary, to solve this problem, we can use the equations for buoyant force, volume, and fraction of volume below the waterline, and apply the given information to find the answers for each part. It may be helpful to write out all the given information and equations in one place to better understand the problem and how to approach it.