Buoyancy is the ability of an object to float.It is related to the object’s density.

Hardeep Dhillon M.P.Ed (IV Sem.) Roll No. 39

DensityDensity is the amount of matter (mass) in a is the amount of matter (mass) in a given volume or spacegiven volume or space

Gasses are the least dense form of matterGasses are the least dense form of matter Liquids are more dense than gasses, but Liquids are more dense than gasses, but

less dense than solidsless dense than solids Solids are the most dense form of matterSolids are the most dense form of matter

  RemindersReminders:: Mass = a fundamental measure of the Mass = a fundamental measure of the

amount of matter in the object amount of matter in the object Volume = the amount of 3-dimensional space Volume = the amount of 3-dimensional space

occupied by an object occupied by an object Density = amount of matter contained by a Density = amount of matter contained by a

given volumegiven volume                                

The upward force exerted by the liquid on any The upward force exerted by the liquid on any object.object.

An upward acting force caused by fluid An upward acting force caused by fluid pressure that keeps object afloat.pressure that keeps object afloat.

All objects faces the force of buoyancy when All objects faces the force of buoyancy when emerged in water.emerged in water.

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                B=mgB=mg                                                                                                                                                                     

                          m = mass of liquid displacedm = mass of liquid displaced

                            g = gravitational accelerationg = gravitational acceleration

Why boats float and Why boats float and elephants sink :buoyancy elephants sink :buoyancy

How does a boat or ship carrying hundreds of How does a boat or ship carrying hundreds of pounds worth of stuff float while that same stuff pounds worth of stuff float while that same stuff would sink to the bottom of the ocean if dumped would sink to the bottom of the ocean if dumped overboard? How come when you're in a pool and overboard? How come when you're in a pool and you stretch your body out flat you float. But, if you stretch your body out flat you float. But, if you wrap your arms around your legs and curl up you wrap your arms around your legs and curl up into a ball you sink?into a ball you sink?

Well, it all has to do with how much water is Well, it all has to do with how much water is pushing against you and a little scientific pushing against you and a little scientific principle called buoyancy or floatation. When you principle called buoyancy or floatation. When you stretch out flat more water pushes against you stretch out flat more water pushes against you since your body is laid out flattersince your body is laid out flatter

Archimedes' PrincipleArchimedes' Principle

A body immersed in a liquid, either wholly or A body immersed in a liquid, either wholly or partially, is buoyed up by a force equal to the partially, is buoyed up by a force equal to the weight of the liquid displaced by the body.weight of the liquid displaced by the body.

Does it sink, or does it float?Does it sink, or does it float?

1. The body will float if the buoyancy is 1. The body will float if the buoyancy is positive (body weight smaller than positive (body weight smaller than weight of displaced liquid). weight of displaced liquid).

2. The body will be suspended if the 2. The body will be suspended if the buoyancy is neutral (body weight equals buoyancy is neutral (body weight equals weight of displaced liquid). weight of displaced liquid).

3. The body will sink if the buoyancy is 3. The body will sink if the buoyancy is negative (body weight larger than weight negative (body weight larger than weight of displaced liquid). of displaced liquid).

Various levels of buoyancy Various levels of buoyancy depending on weight of the depending on weight of the submerging body submerging body

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Apparent WeightApparent Weight..

When the object is immersed in the When the object is immersed in the water, the object weighs less due to the water, the object weighs less due to the buoyant force. buoyant force.

WW′ = ′ = WW −  − BB WW′ is the weight of the object in the fluid′ is the weight of the object in the fluid WW  is the original weight of the object  is the original weight of the object B B is the buoyant forceis the buoyant force

Thank YouThank You

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