We
were discussing the basic definition and derivation of total
pressure; centre
of pressure and we have also secured the expression for total
pressure and centre of pressure for inclined plane surface submerged in liquid in
our previous posts.
Today we will start a new topic i.e. Buoyancy and floatation, in the subject of fluid mechanics, with the help of this post. We will see here the basic concept of Buoyancy, Archimedes principle, Centre of buoyancy, Metacentre, Metacentric height etc.
We will first see here the basic concept of buoyancy or buoyancy force with the help of this post.
Today we will start a new topic i.e. Buoyancy and floatation, in the subject of fluid mechanics, with the help of this post. We will see here the basic concept of Buoyancy, Archimedes principle, Centre of buoyancy, Metacentre, Metacentric height etc.
We will first see here the basic concept of buoyancy or buoyancy force with the help of this post.
Buoyancy or buoyancy force
When
a body is immersed in fluid, an upward force is exerted by the fluid on the
body. This force will be equal to the weight of the fluid displaced by the body
and this force will be termed as force of buoyancy or buoyancy.
Let us consider we have one container filled with water as displayed here in following figure. We have one object of weight 7 N. Let us think that we are now immersing the object in to the liquid i.e. water.
Let us consider we have one container filled with water as displayed here in following figure. We have one object of weight 7 N. Let us think that we are now immersing the object in to the liquid i.e. water.
Once
object will be immersed in the water, some amount of water will be displaced by
the object and one upward force will be applied over the object by the water.
Weight of the displaced water will be equal to this upward force which will be exerted by the water on the object. As we can see from above figure that, water of weight 3N is displaced here and one upward force of 3N is exerted by the water over the object.
Weight of the displaced water will be equal to this upward force which will be exerted by the water on the object. As we can see from above figure that, water of weight 3N is displaced here and one upward force of 3N is exerted by the water over the object.
Conclusion for buoyancy force
Buoyancy
force is the force which will be exerted on the object by the surrounding fluid.
When one object will be immersed in the water, object will push the water and
water will push back the object with as much force as it can.
Force
of buoyancy = Weight of the displaced fluid
Force
of buoyancy = Weight of the object in air – Weight of the object in given water
Positive buoyancy
Force
of buoyancy will be greater than the weight of the object. Hence, object will
float and this case will be termed as positive buoyancy.
Neutral buoyancy
Force
of buoyancy will be equal to the weight of the object. Hence, object will be
suspended in the fluid and this case will be termed as neutral buoyancy.
Negative buoyancy
Force
of buoyancy will be less than the weight of the object. Hence, object will be
sunk and this case will be termed as negative buoyancy.
We will see another topic i.e. Centre of buoyancy in our next post.
Do you have any suggestions? Please write in comment box.
We will see another topic i.e. Centre of buoyancy in our next post.
Do you have any suggestions? Please write in comment box.
Reference:
Fluid mechanics, By R. K. Bansal
Image
Courtesy: Google
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