Motion of an object submerged in water.

AI Thread Summary
The motion of a cylindrical object submerged in water can be described using Newton's second law, where the net force is the difference between the upward buoyancy force and the downward weight. The buoyancy force is defined by the equation B = [1020+0.25z]Volumexgravity, indicating that it varies with depth. In equilibrium, the forces are equal (Fup = Fdown), but for motion to occur, the net force must be considered, leading to the equation Fup - Fdown = ma. This approach clarifies that the object will move if the buoyancy force exceeds its weight. Understanding these dynamics is crucial for analyzing submerged objects' behavior.
aero&astro
Messages
18
Reaction score
0
ignoring drag, how could you describe the motion of a cylindrical object in water, if the upwards buoyancy force is given by a certain equation? (B = [1020+0.25z]Volumexgravity)

I'm not sure if its just Fup = Fdown where Fdown is the weight and Fup is the buoyancy. However it can't be that or else the cylinder wouldn't have motion it would be stationary, wouldn't it?
 
Engineering news on Phys.org
hi aero&astro! :smile:

(try using the X2 icon just above the Reply box :wink:)
aero&astro said:
I'm not sure if its just Fup = Fdown where Fdown is the weight and Fup is the buoyancy. However it can't be that or else the cylinder wouldn't have motion it would be stationary, wouldn't it?

no, Fup = Fdown would be the equilibrium equation

you need (as usual) good ol' Newton's second law …

Fup - Fdown = ma :wink:
 
why is it Fup - Fdown and not Fdown - Fup?
 
Because tiny-tim assumed a reference frame where "up" points to positive values, and "down" points to negative values.
 
Yup! :biggrin:
 
thanks a lot guys, this really helped.
 

Thread 'Race car suspension Class'

Posted June 2024 - 15 years after starting this class. I have learned a whole lot. To get to the short course on making your stock car, late model, hobby stock E-mod handle, look at the index below. Read all posts on Roll Center, Jacking effect and Why does car drive straight to the wall when I gas it? Also read You really have two race cars. This will cover 90% of problems you have. Simply put, the car pushes going in and is loose coming out. You do not have enuff downforce on the right...
View full post »

Thread 'Cantilever help'

I'm trying to decide what size and type of galvanized steel I need for 2 cantilever extensions. The cantilever is 5 ft. The space between the two cantilever arms is a 17 ft Gap the center 7 ft of the 17 ft Gap we'll need to Bear approximately 17,000 lb spread evenly from the front of the cantilever to the back of the cantilever over 5 ft. I will put support beams across these cantilever arms to support the load evenly
View full post »
Thread 'What's the most likely cause for this carbon seal crack?'

Thread 'What's the most likely cause for this carbon seal crack?'

We have a molded carbon graphite seal that is used in an inline axial piston, variable displacement hydraulic pump. One of our customers reported that, when using the “A” parts in the past, they only needed to replace them due to normal wear. However, after switching to our parts, the replacement cycle seems to be much shorter due to “broken” or “cracked” failures. This issue was identified after hydraulic fluid leakage was observed. According to their records, the same problem has occurred...
View full post »

Similar threads

Calculate the max speed at which a submarine rises/dives
Replies
5
Views
2K
Calculating drag of an object under water(Help)
Replies
10
Views
7K
Find Time to Reach Top of Beaker (10 cm)
Replies
16
Views
2K
Should I Use the Total Length of an Object to Calculate Buoyancy?
Replies
10
Views
11K
Diameter of hole vs time to submerge
Replies
8
Views
3K
Buoyancy Force of a Divers "Snorkel" Ping Pong Ball
Replies
1
Views
844
Buoyancy force on the partially submerged object
Replies
1
Views
8K
What Are the Complexities of Buoyancy and Common Misconceptions?
Replies
48
Views
10K
Origin of Upthrust: Displaced Water & Pressure Difference
Replies
5
Views
9K
Force on an object that is stationary in flowing water
Replies
12
Views
6K

Hot Threads

Recent Insights

Back
Top