Calculating Buoyancy and Weight in a Sinking Ship Diorama

In summary, an art student is constructing a ship sinking diorama and is limited in their knowledge of physics to what they have read and what they have learned from experiments. They fill a container with water and push the model under the water to measure the volume. They then add weights to the model to determine how heavy it needs to be to sink and to make it float again.
  • #1
nbontra
16
0
I'm constructing a diorama of a ship sinking, and I haven't been able to find any details on the physics behind it. I'm an art student, so my knowledge in physics is limited to what I read here and in a few books at home.

I'll most likely construct a fish tank that is 4'x1'x1' to contain the water and toy ship. My question is to what formula I would use to determine how heavy to make the toy ship. Is it just a scale issue? Where I could just use the size ratio to figure out the weight? If I go that route, will the amount of water or the size of the tank affect the rate at which it sinks?

Also, I'll be using an air compressor hose to attempt to raise the ship while it is sinking. How does one determine how much air can raise a certain amount of weight underwater?

Thanks!
 
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  • #2
It depends on the volume and mass of the ship. Unless it is a very simple crude shape it is going to be difficult to calculate the volume of the ship.
To measure the volume fill a container to the top with water, push the model under the water and cathc the extra water that overlfows. The volume of this water is the displacement.
Fresh (ie not salt) water weighs 1Kg / litre so your boat has to weigh more than 1Kg for each litre it displaces.
You will probably have to add weights to make it sink.

Then to make it float again you add air from the hose. For every litre of air you add you get 1kg of lift.

With a detailed model you are also going to have problems with air bubbles caught in small details.
You are probabaly ging to have to experiment to get it right.
 
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  • #3
Viscous effects, those which influence the resistance of the ship to the water, are related to the surface area of the ship exposed to the water, and determine a terminal velocity for the sinking ship. Buoyancy, or lack of it, determines the acceleration component of sinking, and is related to the density of the ship minus the density of water displaced by it, as mgb_phys mentioned. Take care to consider (or eliminate) any air bubbles, also using Archimedes' principle! A simple shape that you may want to experiment with is that of a submarine rather than a ship.
 
  • #4
thanks for the info, i surely appreciate it!
 

Related to Calculating Buoyancy and Weight in a Sinking Ship Diorama

1. How does a ship float in water?

A ship floats in water due to the principle of buoyancy, which states that the upward force exerted by a fluid on an object immersed in it is equal to the weight of the displaced fluid. The shape of the ship's hull allows it to displace a large volume of water, creating an upward force that is greater than the weight of the ship itself, allowing it to float.

2. Why do ships sink?

Ships can sink due to a variety of factors, such as damage to the hull, overloading, or taking on too much water. However, the main reason a ship sinks is due to the loss of buoyancy. If the weight of the water inside the ship becomes greater than the buoyant force, the ship will sink.

3. How does the displacement of water affect a sinking ship?

The displacement of water plays a crucial role in a sinking ship. As a ship takes on water, it will displace more water, which in turn increases the weight of the water inside the ship. This increases the weight of the ship, making it harder for the ship to stay afloat and more likely to sink.

4. Can a ship sink even if it is made of a buoyant material?

Yes, a ship can still sink even if it is made of a buoyant material. Buoyancy is dependent on the shape and volume of the object, not the material it is made of. If the ship is damaged or takes on too much water, the weight of the water inside can still overcome the buoyant force, causing the ship to sink.

5. How does the center of mass and center of buoyancy affect a sinking ship?

The center of mass and center of buoyancy play a crucial role in a sinking ship. The center of mass is the point at which the weight of the ship is evenly distributed, while the center of buoyancy is the point at which the upward force of the water is evenly distributed. If the center of mass is below the center of buoyancy, the ship will be stable and less likely to sink. However, if the center of mass is above the center of buoyancy, the ship will become unstable and more likely to sink.

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