# Buoyancy questions: Submerged vs Floating

• PhysicsTyro
In summary, the conversation discusses the difference between submerged objects and floating objects, specifically in regards to the Force of Buoyancy and volume. The speaker also asks for clarification on the equations related to buoyancy and expresses a desire to better understand the concept.
PhysicsTyro
Is there a difference in submerged objects and floating objects? I know in floating objects that the Force of Buoyancy has to equal the Force of the object, but I'm not sure about submerged objects. What exactly is a submerged object?

Another question I have: what exactly does volume have to do with buoyancy?

Lastly: I was given three equations and I wanted to know when and how I used them:

Fnet = pVdisplacementg

Fnet = mg-pVg

mg = pVg (or m=pV)

All help is appreciated and sorry if these questions seem rather like 'duh' questions, but I simply don't understand buoyancy and I don't want to fall behind in class.

My bet is that this thread is the next one to get sent downrange to the Homework forum...

Yes, there is a difference between submerged and floating objects. Submerged objects are completely or partially immersed in a fluid (such as water) and their weight is supported by the fluid. This means that the force of buoyancy is greater than the weight of the object, causing it to float. On the other hand, floating objects are objects that are able to remain at the surface of the fluid without sinking, and the force of buoyancy is equal to the weight of the object.

To determine whether an object will sink, float, or remain submerged, we need to consider two main factors: the density of the object and the density of the fluid it is submerged in. If the object is denser than the fluid, it will sink. If the object is less dense than the fluid, it will float. If the object and the fluid have the same density, the object will remain submerged at a certain level.

Volume plays a crucial role in determining buoyancy. The volume of an object affects its density, and therefore its ability to float or sink. The more volume an object has, the more water it will displace, and the greater the force of buoyancy will be. This is why larger objects tend to float more easily than smaller objects.

The equations you were given are all related to the concept of buoyancy. The first equation, Fnet = pVdisplacementg, calculates the net force acting on an object submerged in a fluid. Fnet represents the net force, p is the density of the fluid, Vdisplacement is the volume of the fluid displaced by the object, and g is the acceleration due to gravity. This equation is used to determine whether an object will float or sink.

The second equation, Fnet = mg-pVg, calculates the net force acting on an object floating on the surface of a fluid. Fnet represents the net force, m is the mass of the object, p is the density of the fluid, V is the volume of the object, and g is the acceleration due to gravity. This equation is used to determine the buoyant force acting on the object and whether it will remain at the surface or sink.

The third equation, mg = pVg (or m=pV), calculates the weight of an object and is used to compare it to the buoyant force acting on the object. If the weight is greater than the buoyant force, the object will sink. If the weight

## 1. What is buoyancy and how does it work?

Buoyancy is the upward force that a fluid exerts on an object. It works based on the principle of Archimedes' law, which states that the buoyant force on an object is equal to the weight of the fluid it displaces.

## 2. What determines whether an object will float or sink?

An object will float if its weight is less than the buoyant force acting on it. This is because the upward buoyant force will be greater than the downward force of gravity, causing the object to rise to the surface. An object will sink if its weight is greater than the buoyant force.

## 3. Why do some objects float while others sink?

The density of an object determines whether it will float or sink. Objects with a lower density than the fluid they are in will float, while objects with a higher density will sink. This is why objects like wood and plastic, which have lower densities than water, float while objects like rocks and metals, which have higher densities, sink.

## 4. How does the shape and size of an object affect its buoyancy?

The shape and size of an object can affect its buoyancy in two ways. First, a larger object will displace more fluid, creating a greater upward buoyant force. Second, the shape of the object can affect how much of it is submerged in the fluid, which can also impact the buoyant force. For example, a flat object will have more surface area and therefore more buoyant force than a compact object of the same weight.

## 5. What is the difference between submerged and floating objects in terms of buoyancy?

A submerged object is completely underwater and experiences an upward buoyant force equal to the weight of the fluid it displaces. A floating object is partially submerged and experiences an upward buoyant force that is less than its weight, causing it to float at the surface. In both cases, the buoyant force is the result of the object displacing a certain amount of fluid.

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