Designing a Buoy Tether: Force Analysis and Excel Spreadsheet Solution

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In summary, the problem involves a buoy in the form of a vertical right circular cylinder made of glass-fiber-reinforced plastic, tethered to the bottom of a river with a cable that is 80 feet long. The cable is designed to snap at a water depth exceeding 90 feet. The Archimedes Principle and force balance on the buoy can be used to compute the force on the cable at different river depths. To start, the calculation can be performed by hand for one particular case, such as a water depth of 85 feet.
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Homework Statement


Consider a buoy in the form of a vertical right circular cylinder of outside diameter (D) of 8 feet, and
height (H) of 12 feet. The buoy is a hollow cylinder formed of glass-fiber-reinforced plastic (FRP)
that is ½-inch thick. The buoy is to be placed in a large river and tethered to the bottom by a cable
that is 80 feet long
The cable is supposed to snap if the water depth exceeds 90 feet. Set up an
Excel spreadsheet to compute the force on the cable at different river depths and the force at which
the cable should be designed to snap.


Homework Equations


Archimedes Pinciple: mass of obj- apparent mass of obj= Density of water * vol of obj
The force on the cable can be computed from a force balance on the buoy.
The downward force due to gravity is the total mass of the buoy multiplied by gravitational
acceleration

The Attempt at a Solution


Not sure how to start this, I have to solve it in excel but don't know where to begin
 
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Shnitzel said:

Homework Statement


Consider a buoy in the form of a vertical right circular cylinder of outside diameter (D) of 8 feet, and
height (H) of 12 feet. The buoy is a hollow cylinder formed of glass-fiber-reinforced plastic (FRP)
that is ½-inch thick. The buoy is to be placed in a large river and tethered to the bottom by a cable
that is 80 feet long
The cable is supposed to snap if the water depth exceeds 90 feet. Set up an
Excel spreadsheet to compute the force on the cable at different river depths and the force at which
the cable should be designed to snap.


Homework Equations


Archimedes Pinciple: mass of obj- apparent mass of obj= Density of water * vol of obj
The force on the cable can be computed from a force balance on the buoy.
The downward force due to gravity is the total mass of the buoy multiplied by gravitational
acceleration

The Attempt at a Solution


Not sure how to start this, I have to solve it in excel but don't know where to begin

Hi Shnitzel, Welcome to Physics Forums.

To start off, why not perform the calculation by hand for one particular case. That will at least tell you what constants, variables and formulas you'll need to implement.

So, suppose that at some time the river is 85 feet deep. What's the tension on the buoy cable?
 

1. What is a buoy tether?

A buoy tether is a line or cable that connects a buoy to an anchor or other fixed structure in the water. It is used to keep the buoy in a specific location and prevent it from drifting away.

2. How is a buoy tether designed?

The design of a buoy tether depends on various factors such as the location and depth of the water, the expected wind and wave conditions, and the weight and size of the buoy. It typically involves determining the appropriate length, material, and strength of the tether to withstand the forces it will encounter.

3. What materials are commonly used for buoy tethers?

The most common materials used for buoy tethers are synthetic fibers such as nylon, polypropylene, and polyester. These materials are lightweight, strong, and resistant to corrosion and degradation from exposure to water and sunlight.

4. How long should a buoy tether be?

The length of a buoy tether depends on the depth of the water and the expected movement of the buoy. It should be long enough to allow the buoy to move with the waves and currents without becoming entangled, but not so long that it drags on the bottom of the water or gets caught on other objects.

5. How often should buoy tethers be replaced?

Buoy tethers should be regularly inspected for any signs of wear and tear, such as fraying or weakening of the material. The frequency of replacement will depend on the specific conditions and usage of the buoy, but it is recommended to replace the tether at least once a year to ensure its reliability.

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