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Author Topic: How does being afloat in a boat affect the weight of a bowling ball?  (Read 3942 times)

Forrest Newton

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Forrest Newton  asked the Naked Scientists:
   
Here is a puzzling question,
 
Put a bowling ball in a large bucket of water, the weight of the bucket would be bucket + water + bowling ball
 
Next put the bowling ball in the bucket in a boat in the water.
 
There are no difference in forces as in water pressure under the boat or around the sides of the boat.

How can you explain there is a difference in weight in bucket with or without bowling ball?
 
Forrest D. Newton

What do you think?
« Last Edit: 23/10/2010 09:30:14 by _system »


 

Offline donchiragjain10036

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I think I can answer that !

The principles behind the phenomenon are the laws of flotations.

The weight of the water that is expelled by the bowling ball is equal to the weight of the bowling ball.

 
 

Offline imatfaal

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The boat will ride slightly lower in the water if you add the extra few kilograms of a bucket and bowling ball.  As Donch said it will displace more water than before - the volume of water displaced will have a mass the same as the additional cargo (the b-ball and bucket).
 

Offline Bill S

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F N, Lets take your points one at a time.


“Put a bowling ball in a large bucket of water, the weight of the bucket would be bucket + water + bowling ball.”

If the bucket was full, the weight would remain the same because the displaced water will be lost; otherwise the overall weight will increase.

“Next put the bowling ball in the bucket in a boat in the water.”

 Weight of the boat will increase by bucket + water + ball.

“There are no difference in forces as in water pressure under the boat or around the sides of the boat.”

The increased weight causes the boat to displace more water, so there is a slight change in pressure under/around the boat.

How can you explain there is a difference in weight in bucket with or without bowling ball?

The only difference will depend on whether or not the bucket was full, as in the first point above.

I am not a scientist, these are only my thoughts, so could be wrong.
 

Offline maffsolo

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Quote
Put a bowling ball in a large bucket of water, the weight of the bucket would be bucket + water + bowling ball

I interpret, No loss of displacement of water, all the water is still in the bucket with the ball.

Quote
Next put the bowling ball in the bucket in a boat in the water.
 
Is this the same bucket water and ball?

If so I will state my interpretation: by rewriting this:

Next we have a boat, large enough to hold the bucket afloat, in a separate body of water!
Place the bucket we have , bucket water and bowling ball, in the boat.
Is this fair game?

Quote
There is no difference in forces as in water pressure under the boat or around the sides of the boat.
Are we neglecting the buoyancy of the boat?
If so we need not introduce the boat into the problem.

Quote
How can you explain there is a difference in weight in bucket with or without bowling ball?
 

First let’s do it without the bowling ball to get a baseline reference.
Place the empty bucket into a reasonably deep portion of water.
Mark the outside wall of the bucket, as  its buoyancy level (A).
It may be easier to read if you mark it in 3 adjacent locations around the wall of the bucket.

This is where the water level is reaching at the side of the bucket.
 This will distinguish the weight of the bucket by itself.

Before continuing, above this point,  arbitrarily mark a label (B), closest to the top would be also better placement the same way (A) is labeled.

Now as the bucket floats, without holding the bucket, place the bowling ball in the bucket.
 This level (B) will designate the ball in the bucket is to darn heavy. Need a taller bucket
 The (3) “B’s”  will designate for Bye Bucket and ball.
I’ll go to my room and sit in the corner now .
« Last Edit: 23/10/2010 22:45:35 by maffsolo »
 

Offline maffsolo

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I think I can answer that !

The principles behind the phenomenon are the laws of flotations.

The weight of the water that is expelled by the bowling ball is equal to the weight of the bowling ball.

 

I think that the volume of water displaced by the bowling ball, is equal to the volume of the bowling ball.
Not the weight!
Unless the bowling ball was made of water.
 

Offline maffsolo

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As Donch said it will displace more water than before - the volume of water displaced will have a mass the same as the additional cargo (the b-ball and bucket).

Am I correctly interpreting this as seperate items?

"the volume of water displaced will have a mass...

the same as the additional cargo (the b-ball and bucket)..."

 each of them having the same mass as before?
or
they have the same mass as each other?
« Last Edit: 23/10/2010 23:47:39 by maffsolo »
 

Offline Joe L. Ogan

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I believe what he is trying to say is that the bowling ball is heavier than water.  If this is true, when placed in the boat, the extra weight of the bowling ball will cause the boat to displace a greater amount of water.  thanks for comments.  Joe L. Ogan
 

Offline maffsolo

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I believe what he is trying to say is that the bowling ball is heavier than water.  If this is true, when placed in the boat, the extra weight of the bowling ball will cause the boat to displace a greater amount of water.  thanks for comments.  Joe L. Ogan

Oh ok I see.

Forrest Newton  asked the Naked Scientists:
 
There are no difference in forces as in water pressure under the boat or around the sides of the boat.


This is what is confusing to me???
I looked at this as being dismissed

If the weight of the boat is then increased to displace the water, wouldn't there be a pressure?

 

Offline Geezer

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I suspect the boat is unable to to get out of the seabed because it's a nervous wreck.
 

Offline donchiragjain10036

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I think I can answer that !

The principles behind the phenomenon are the laws of flotations.

The weight of the water that is expelled by the bowling ball is equal to the weight of the bowling ball.

 

I think that the volume of water displaced by the bowling ball, is equal to the volume of the bowling ball.
Not the weight!
Unless the bowling ball was made of water.

The amount of weight lost by the bowling bowl is equal to the weight of the volume of water that the bowling ball displaces.
 

Offline Bill S

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Quote
The increased weight causes the boat to displace more water, so there is a slight change in pressure under/around the boat.
Quote
If the weight of the boat is then increased to displace the water, wouldn't there be a pressure?
Are we going round in circles?

Maffsolo, your post(328044)covered the subject well, but it was so pedantic that I was surprised you didn't mention that placing "the empty bucket into a reasonably deep portion of water" would almost certainly result in a capsized bucket.

Perhaps Geezer's comment should be the last word! 
 

Offline Geezer

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Quote
The increased weight causes the boat to displace more water, so there is a slight change in pressure under/around the boat.
Quote
If the weight of the boat is then increased to displace the water, wouldn't there be a pressure?
Are we going round in circles?

Maffsolo, your post(328044)covered the subject well, but it was so pedantic that I was surprised you didn't mention that placing "the empty bucket into a reasonably deep portion of water" would almost certainly result in a capsized bucket.

Perhaps Geezer's comment should be the last word! 

It was only slightly tongue in cheek. There is no mention of whether the boat is afloat or aanchor.


EDIT: Woops, I'll have to take that back. I see afloat is mentioned in the title  [:I]
« Last Edit: 24/10/2010 17:34:04 by Geezer »
 

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