SOLUTION: A right circular cone with top width 24cm and altitude 8cm is filled with water. A spherical steel ball with radius 3.0cm is submerged in the cone. Find the volume of water below t

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Question 1189457: A right circular cone with top width 24cm and altitude 8cm is filled with water. A spherical steel ball with radius 3.0cm is submerged in the cone. Find the volume of water below the sphere.
Found 2 solutions by greenestamps, Edwin McCravy:
Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


Not clear....

I think it is safe to say the only reasonable interpretation of "volume of water below the sphere" means below the lowest point of the sphere.

But to calculate that, we need to know HOW DEEP the sphere is submerged in the cone. Simply saying the sphere is submerged in the cone is not enough.


Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
Unlike the other tutor, I will assume the ball is heavy 
enough to sink all the way down and touch the sides of 
the cone.  No offense, Greenestamps! lol

Here is the way it looks:



It's easy to see that all 6 right triangles DFC, EFC, OPA, OPB, 
APC, and BPC are similar. Here's a mid-cross-section 



By using the Pythagorean theorem to calculate the hypotenuse CD = 4√(13),
we see that this ratio holds for all 6 right triangles 

shorter leg : longer leg : hypotenuse = 8 : 12 : 4sqrt%2813%29

Dividing through by 4

shorter leg : longer leg : hypotenuse = 2 : 3 : sqrt%2813%29

Below we will draw the kite ACBO with all the lengths which
we calculate by ratio and proportion of similar triangles
(You don't need to calculate them all).



So the radius of the cone at the bottom (that the sphere "sits in") is 

AP%22%22=%22%226%2Fsqrt%2813%29

and the height of that cone is

CP%22%22=%22%224%2Fsqrt%2813%29

We compute its volume by the formula:

V%22%22=%22%22expr%281%2F3%29%2Api%2Ar%5E2%2Ah

V%22%22=%22%22expr%281%2F3%29%2Api%2A%286%2Fsqrt%2813%29%29%5E2%284%2Fsqrt%2813%29%29%22%22=%22%22expr%281%2F3%29%2Api%2A%2836%2F13%29%284%2Fsqrt%2813%29%29%22%22=%22%22%2848pi%29%2F%2813sqrt%2813%29%29

However, we see that the volume we want is not the entire cone, because the cone
is "dished out" by the sphere sitting on it.  The "dished out" part is a cap of
the sphere.  So we must calculate the volume of the cap of the sphere which
dishes out the cone, so we can subtract it from the above result.  The formula
for the volume of the cap of a sphere is

V%22%22=%22%22expr%281%2F3%29pi%2Ah%5E2%283r-h%29 

where r = radius of the sphere = 3, and 
h = height of the cap.

We calculate the height of the cap, PQ:

PQ = OQ - OP.  OQ is a radius of the sphere, so OQ = 3. So

PQ%22%22=%22%223-9%2Fsqrt%2813%29  

So the volume of the cap is

V%22%22=%22%22

That simplifies to expr%2836pi%2F169%29%2869sqrt%2813%29-247%29

So we subtract that from  %2848pi%29%2F%2813sqrt%2813%29%29 and get the
volume of water below the sphere as

%2848pi%29%2F%2813sqrt%2813%29%29%22%22-%22%22expr%2836pi%2F169%29%2869sqrt%2813%29-247%29

which simplifies to:

expr%2812%2F169%29pi%2A%28793+-+207sqrt%2813%29%29 cubic centimeters.

Edwin