Archimedes Principle
Archimedes Principle
Archimedes’ Principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces. This principle is fundamental in fluid mechanics and has numerous applications in various fields.
When an object is placed in a fluid, it experiences an upward force due to the pressure difference between the top and bottom surfaces of the object. This difference in pressure creates a net upward force known as buoyancy. The magnitude of the buoyant force is equal to the weight of the fluid displaced by the object.
Archimedes’ Principle is independent of the object’s shape, density, or weight. It applies to both fully submerged and partially submerged objects. For floating objects, the buoyant force is equal to the weight of the object, resulting in a state of equilibrium.
This principle has practical applications in determining the density of objects, designing ships and submarines, and understanding fluid dynamics. It also explains why objects appear lighter when submerged in water or other fluids.
What is the Archimedes’ Principle?
Archimedes’ Principle Explanation
Archimedes’ Principle states that when an object is immersed in a fluid, it experiences an upward buoyant force equal to the weight of the fluid displaced by the object. This principle is fundamental to understanding the behavior of objects in fluids and has numerous applications in various fields.
Explanation:
Consider an object of irregular shape submerged in a fluid, such as water. The fluid exerts pressure on the object’s surface, which varies with depth. The pressure is greater at the bottom of the object than at the top. This difference in pressure creates a net upward force known as the buoyant force.
The magnitude of the buoyant force is equal to the weight of the fluid displaced by the object. This can be understood by imagining the object replaced by an equal volume of the fluid. The weight of the displaced fluid is the same as the buoyant force acting on the object.
Examples:

Floating Objects: Objects less dense than the fluid they are immersed in will experience a buoyant force greater than their weight, causing them to float. For instance, a boat floats on water because the average density of the boat is less than the density of water.

Submarines: Submarines can control their buoyancy by adjusting the amount of water they take in or expel from ballast tanks. When they want to submerge, they increase their density by taking in water, which reduces the buoyant force and allows them to sink. To resurface, they expel water, decreasing their density and increasing the buoyant force.

Hydrometers: Hydrometers are instruments used to measure the density of liquids. They work based on Archimedes’ Principle. A hydrometer floats in the liquid, and the depth to which it sinks is inversely proportional to the liquid’s density.

Hot Air Balloons: Hot air balloons rise because the hot air inside the balloon is less dense than the cooler air outside. The buoyant force acting on the balloon is greater than its weight, causing it to ascend.

Scuba Diving: Scuba divers wear buoyancy compensators (BCs) to control their buoyancy underwater. By adding or releasing air from the BC, divers can adjust their density and achieve neutral buoyancy, allowing them to remain suspended at a desired depth without sinking or floating rapidly.
In summary, Archimedes’ Principle explains the upward buoyant force experienced by objects immersed in fluids. This principle has practical applications in various fields, including shipbuilding, submarine design, density measurement, and scuba diving.
Archimedes’ Principle Formula
Archimedes’ Principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces. This principle is fundamental to understanding buoyancy and floatation.
The Archimedes’ Principle formula is given by:
$$F_b = \rho g V$$
Where:
 (F_b) is the buoyant force in Newtons (N)
 (\rho) is the density of the fluid in kilograms per cubic meter (kg/m³)
 (g) is the acceleration due to gravity (approximately 9.8 m/s²)
 (V) is the volume of the fluid displaced by the body in cubic meters (m³)
To understand the Archimedes’ Principle formula, consider the following example:

A solid block of wood with a volume of 0.01 cubic meters (m³) is placed in a container filled with water. The density of water is approximately 1000 kg/m³.

The buoyant force acting on the block of wood is:
$$F_b = \rho g V = (1000 kg/m³)(9.8 m/s²)(0.01 m³) = 98 N$$
This means that the water exerts an upward force of 98 N on the block of wood, which is equal to the weight of the water displaced by the block.
Archimedes’ Principle has numerous applications in various fields, including:
 Shipbuilding: Ships float on water because the buoyant force acting on them is greater than their weight.
 Hydrometers: These instruments measure the density of liquids based on the principle of buoyancy.
 Submarines: Submarines can control their buoyancy by adjusting the amount of water they take in or release.
 Hot air balloons: Hot air balloons rise because the hot air inside the balloon is less dense than the cooler air outside, creating a net upward buoyant force.
Understanding Archimedes’ Principle and its formula is crucial for comprehending the behavior of objects in fluids and has practical applications in diverse areas of science and engineering.
Archimedes’ Principle Derivation
Archimedes’ Principle Derivation
Archimedes’ principle states that the buoyant force on an object submerged in a fluid is equal to the weight of the fluid displaced by the object. This principle can be derived using the following steps:
 Consider a fluid at rest with a uniform density ρ.
 Imagine a small object of volume ΔV submerged in the fluid.
 The pressure at the top of the object is P1, and the pressure at the bottom of the object is P2.
 The difference in pressure between the top and bottom of the object is ΔP = P2  P1.
 The buoyant force on the object is equal to the difference in pressure times the area of the object, or FB = ΔP * A.
 The weight of the fluid displaced by the object is equal to the density of the fluid times the volume of the object, or W = ρ * ΔV.
 Setting the buoyant force equal to the weight of the fluid displaced, we get FB = W, or ΔP * A = ρ * ΔV.
 Dividing both sides of the equation by ΔV, we get ΔP/ΔV = ρ.
 Taking the limit as ΔV approaches zero, we get dP/dV = ρ.
 This equation states that the pressure gradient in a fluid is equal to the density of the fluid.
Example:
A block of wood with a volume of 100 cm3 is submerged in water. The density of water is 1 g/cm3. What is the buoyant force on the block of wood?
The buoyant force on the block of wood is equal to the weight of the water displaced by the block of wood. The weight of the water displaced is equal to the density of the water times the volume of the block of wood, or W = ρ * ΔV = 1 g/cm3 * 100 cm3 = 100 g.
Therefore, the buoyant force on the block of wood is 100 g.
Archimedes’ Principle Examples
Archimedes’ Principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces. This principle has numerous applications and can be observed in various everyday situations. Here are some examples:
1. Floating Objects:
 Ships float on water because the buoyant force exerted by the water is greater than or equal to the weight of the ship. The shape of the ship is designed to maximize the volume of water displaced, increasing the buoyant force.
2. Submarines:
 Submarines can submerge and surface by controlling their buoyancy. By adjusting the amount of water they take in or expel from ballast tanks, they can change their overall density and achieve neutral buoyancy, allowing them to remain suspended underwater.
3. Hydrometers:
 Hydrometers are instruments used to measure the density of liquids. They work based on Archimedes’ Principle. The depth to which a hydrometer sinks in a liquid is inversely proportional to the liquid’s density.
4. Hot Air Balloons:
 Hot air balloons rise because the hot air inside the balloon is less dense than the cooler air outside. The difference in density creates an upward buoyant force that lifts the balloon.
5. Diving:
 Scuba divers wear buoyancy compensators (BCs) to control their buoyancy underwater. By adding or releasing air from the BC, divers can adjust their overall density and achieve neutral buoyancy, allowing them to remain suspended at a desired depth.
6. Fishing Floats:
 Fishing floats are designed to keep fishing lines and baits suspended in water. They are made of materials with low density, such as cork or plastic, which displace a significant volume of water, creating enough buoyant force to keep them afloat.
7. Icebergs:
 Icebergs float in water because ice is less dense than liquid water. The buoyant force exerted by the water keeps the iceberg afloat, with only a small portion visible above the waterline.
8. Mercury Barometers:
 Mercury barometers measure atmospheric pressure using the principle of buoyancy. The height of the mercury column in the barometer is determined by the weight of the air pressing down on the surface of the mercury, which is balanced by the buoyant force exerted by the air on the mercury.
These examples illustrate the practical applications of Archimedes’ Principle in various fields, from transportation and engineering to scientific measurements and everyday observations. Understanding this principle allows us to comprehend and predict the behavior of objects in fluids and design technologies that utilize buoyancy for different purposes.
Archimedes’ Principle Experiment
Archimedes’ Principle Experiment
Archimedes’ principle states that the buoyant force on an object submerged in a fluid is equal to the weight of the fluid displaced by the object. This principle can be demonstrated through a simple experiment.
Materials:
 A graduated cylinder
 Water
 A small object that will sink in water (e.g., a metal washer)
 A string
 A scale
Procedure:
 Fill the graduated cylinder with water to a certain level.
 Tie the string to the object and lower it into the graduated cylinder until it is completely submerged.
 Observe the water level in the graduated cylinder.
 Remove the object from the graduated cylinder and weigh it.
 Calculate the weight of the water displaced by the object by subtracting the initial water level from the final water level and multiplying the difference by the density of water (1 g/mL).
Observations:
When the object is submerged in water, the water level in the graduated cylinder rises. This indicates that the object is displacing water.
The weight of the water displaced by the object is equal to the weight of the object. This demonstrates Archimedes’ principle.
Applications:
Archimedes’ principle has many applications in everyday life. For example, it is used to design ships, submarines, and other watercraft. It is also used to measure the density of objects.
Example:
A ship floats on water because the buoyant force of the water is greater than the weight of the ship. The ship displaces a large amount of water, which creates a large buoyant force. This buoyant force is greater than the weight of the ship, so the ship floats.
Archimedes’ Principle Applications
Archimedes’ Principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces. This principle has numerous applications in various fields, including:
1. Buoyancy and Floating:
 Ships and submarines: Archimedes’ Principle explains why ships float on water. The buoyant force acting on a ship is equal to the weight of the water displaced by the ship’s submerged portion. This allows ships to remain afloat even though they are much denser than water.
 Hydrometers: These instruments measure the specific gravity of liquids by determining the depth to which they sink in the liquid. The denser the liquid, the less the hydrometer sinks.
2. Fluid Mechanics and Engineering:
 Dams and locks: Archimedes’ Principle is crucial in designing dams and locks. Dams hold back large volumes of water, and the buoyant force acting on the dam’s structure must be considered to ensure its stability. Locks allow ships to travel between bodies of water at different elevations by using gates to control the water level and the buoyant force acting on the ships.
 Fluid flow measurement: Archimedes’ Principle is used in devices like rotameters and turbine flowmeters to measure the flow rate of fluids. These devices utilize the principle to determine the buoyant force exerted on a rotating element or impeller within the fluid stream.
3. Marine Engineering and Oceanography:
 Submarines: Submarines can submerge and surface by controlling their buoyancy. By adjusting the amount of water they take in or expel from ballast tanks, submarines can alter their overall density and achieve neutral buoyancy, allowing them to remain suspended underwater.
 Marine salvage: Archimedes’ Principle is applied in lifting sunken ships and other objects from the water. By attaching buoyant devices or pontoons to the submerged object, the overall density of the system is reduced, increasing the buoyant force and facilitating the object’s recovery.
4. Aerospace Engineering:
 Hot air balloons: Archimedes’ Principle explains why hot air balloons rise. The heated air inside the balloon is less dense than the surrounding cooler air, creating a difference in buoyant forces that causes the balloon to ascend.
5. Medical Applications:
 Hydrometry: Archimedes’ Principle is used in medical devices like hydrometers to measure the specific gravity of urine, which can indicate certain medical conditions.
6. Geological Applications:
 Measuring rock density: Archimedes’ Principle is employed in determining the density of rock samples. By measuring the weight of a rock sample in air and then submerged in water, the buoyant force can be calculated, allowing for the determination of the rock’s density.
These examples illustrate the wideranging applications of Archimedes’ Principle in various fields, from engineering and physics to marine science and medicine. Understanding and utilizing this principle has enabled humans to design and develop technologies that harness the power of buoyancy and fluid mechanics for practical purposes.
Submarine:
Submarine
A submarine is a humanmade underwater vessel designed to operate below the surface of the water. Submarines are used for a variety of purposes, including military operations, scientific research, and commercial activities.
History of Submarines
The first submarines were developed in the 17th century, but they were not widely used until the 19th century. During the American Civil War, the Confederate Navy used submarines to attack Union ships. In World War I, submarines were used by both sides to sink enemy ships and disrupt supply lines. In World War II, submarines played a major role in the Battle of the Atlantic, where German Uboats sank thousands of Allied ships.
Types of Submarines
There are many different types of submarines, each designed for a specific purpose. Some of the most common types of submarines include:
 Attack submarines are designed to sink enemy ships and submarines. They are typically armed with torpedoes and missiles.
 Ballistic missile submarines are designed to launch nuclear missiles from underwater. They are typically armed with intercontinental ballistic missiles (ICBMs).
 Cruise missile submarines are designed to launch cruise missiles from underwater. They are typically armed with Tomahawk cruise missiles.
 Research submarines are designed for scientific research. They are typically equipped with a variety of sensors and cameras.
 Commercial submarines are used for a variety of commercial activities, such as oil exploration and salvage operations.
How Submarines Work
Submarines are able to submerge and surface by controlling their buoyancy. Buoyancy is the upward force exerted by water on an object. When a submarine is submerged, it is less dense than the water around it, so it floats. When a submarine surfaces, it is more dense than the water around it, so it sinks.
Submarines control their buoyancy by using ballast tanks. Ballast tanks are compartments that can be filled with water or air. When a submarine wants to submerge, it fills its ballast tanks with water. This makes the submarine more dense than the water around it, so it sinks. When a submarine wants to surface, it pumps the water out of its ballast tanks. This makes the submarine less dense than the water around it, so it floats.
Submarines also use propellers to move through the water. Propellers are blades that rotate to create thrust. When a submarine wants to move forward, it turns its propellers. This creates thrust that pushes the submarine through the water.
Submarine Safety
Submarines are complex machines that can be dangerous to operate. There are a number of safety features that are built into submarines to help prevent accidents. Some of the most common safety features include:
 Emergency escape hatches allow the crew to escape from a submarine in the event of an emergency.
 Fire suppression systems help to put out fires on board a submarine.
 Oxygen generators provide the crew with oxygen to breathe.
 Carbon dioxide scrubbers remove carbon dioxide from the air on board a submarine.
Submarines in the Future
Submarines are an important part of the modern military and scientific communities. They are likely to continue to play a vital role in these areas for many years to come. As technology advances, submarines will become even more capable and versatile.
Hotair balloon:
Hotair balloon:
A hotair balloon is a lighterthanair aircraft that uses hot air to generate lift. The balloon is made of a lightweight fabric envelope that is filled with hot air from a burner. The hot air rises, carrying the balloon up into the sky.
Hotair balloons have been used for centuries, and they are still a popular form of transportation and recreation today. They are often used for sightseeing, and they can also be used for racing and other competitions.
How do hotair balloons work?
Hotair balloons work on the principle of buoyancy. Buoyancy is the upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In the case of a hotair balloon, the fluid is air.
The hot air inside the balloon is less dense than the cold air outside the balloon. This difference in density creates a buoyant force that pushes the balloon up into the sky. The greater the difference in density, the greater the buoyant force will be.
What are the different parts of a hotair balloon?
The main parts of a hotair balloon are:
 The envelope: The envelope is the main body of the balloon. It is made of a lightweight fabric that is airtight and heatresistant.
 The burner: The burner is used to heat the air inside the balloon. It is usually located at the bottom of the balloon.
 The basket: The basket is where the passengers and pilot of the balloon ride. It is usually made of wicker or rattan.
 The rigging: The rigging is the system of ropes and pulleys that is used to control the balloon.
How do you fly a hotair balloon?
To fly a hotair balloon, the pilot uses the burner to heat the air inside the balloon. This causes the balloon to rise. The pilot can control the direction of the balloon by using the rigging.
Hotair balloons are very sensitive to changes in temperature. If the air inside the balloon gets too hot, the balloon will rise too quickly and could burst. If the air inside the balloon gets too cold, the balloon will sink.
What are the safety features of a hotair balloon?
Hotair balloons are equipped with a number of safety features, including:
 A parachute: The parachute is used to slow down the balloon in the event of an emergency.
 A fire extinguisher: The fire extinguisher is used to put out any fires that may occur.
 A first aid kit: The first aid kit is used to treat any injuries that may occur.
Hotair ballooning is a safe and enjoyable way to travel and see the world from a different perspective.
Hydrometer:
A hydrometer is an instrument used to measure the specific gravity or density of a liquid. It is a glass or metal float with a weighted bulb at one end and a graduated stem at the other. The hydrometer is placed in the liquid, and the depth to which it sinks is measured. This depth is then used to determine the specific gravity or density of the liquid.
Hydrometers are used in a variety of applications, including:
 Measuring the alcohol content of alcoholic beverages. The specific gravity of an alcoholic beverage is directly proportional to its alcohol content. By measuring the specific gravity of a beverage, it is possible to determine its alcohol content.
 Measuring the density of liquids. The density of a liquid is its mass per unit volume. By measuring the specific gravity of a liquid, it is possible to determine its density.
 Determining the purity of liquids. The specific gravity of a liquid can be used to determine its purity. For example, the specific gravity of water is 1.000. If the specific gravity of a sample of water is less than 1.000, it means that the water is not pure.
There are a variety of different types of hydrometers, each designed for a specific purpose. Some of the most common types of hydrometers include:
 Alcoholometers are used to measure the alcohol content of alcoholic beverages.
 Densimeters are used to measure the density of liquids.
 Salinometers are used to measure the salinity of water.
 Urinometers are used to measure the specific gravity of urine.
Hydrometers are a simple and inexpensive way to measure the specific gravity or density of a liquid. They are used in a variety of applications, and they are an essential tool for anyone who works with liquids.
Here are some examples of how hydrometers are used:
 In the brewing industry, hydrometers are used to measure the alcohol content of beer.
 In the wine industry, hydrometers are used to measure the sugar content of grapes.
 In the dairy industry, hydrometers are used to measure the fat content of milk.
 In the automotive industry, hydrometers are used to measure the specific gravity of antifreeze.
 In the medical field, hydrometers are used to measure the specific gravity of urine.
Hydrometers are a versatile tool that can be used in a variety of applications. They are an essential tool for anyone who works with liquids.
Frequently Asked Questions – FAQs
What does Archimedes Principle state?
Archimedes’ Principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces. This principle is fundamental to understanding buoyancy and floatation.
Key Points:

Buoyant Force: The buoyant force is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. It is directed vertically upward and acts at the center of buoyancy, which is the centroid of the displaced fluid.

Equal to Weight of Displaced Fluid: The magnitude of the buoyant force is equal to the weight of the fluid displaced by the immersed object. This means that the amount of fluid displaced determines the strength of the buoyant force.

Density and Buoyancy: The density of the fluid plays a crucial role in buoyancy. Denser fluids exert a greater buoyant force compared to less dense fluids. This is because denser fluids have more mass per unit volume, resulting in a higher weight of displaced fluid.

Floating and Sinking: Objects float when the buoyant force acting on them is greater than or equal to their weight. Conversely, objects sink when the buoyant force is less than their weight.
Examples:

Boat Floating: A boat floats on water because the buoyant force exerted by the water is greater than the weight of the boat. The shape of the boat and the air trapped inside contribute to increasing the volume of displaced water, resulting in a larger buoyant force.

Submarine Submerging: A submarine can submerge by increasing its density. This is achieved by taking in water, which increases the submarine’s weight and reduces the buoyant force. When the submarine’s density becomes greater than the density of the surrounding water, it sinks.

Hot Air Balloon: A hot air balloon rises because the hot air inside the balloon is less dense than the cooler air outside. The less dense hot air creates a greater buoyant force, causing the balloon to ascend.

Hydrometers: Hydrometers are instruments used to measure the density of liquids. They work based on Archimedes’ Principle. A hydrometer floats in a liquid, and the depth to which it sinks is inversely proportional to the density of the liquid.
In summary, Archimedes’ Principle explains the concept of buoyancy and how it affects objects immersed in fluids. It states that the buoyant force acting on an object is equal to the weight of the fluid displaced by that object. This principle has practical applications in various fields, including shipbuilding, submarine design, and fluid mechanics.
Who discovered the Archimedes’ Principle?
Who Discovered Archimedes’ Principle?
Archimedes’ principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces. This principle is fundamental to understanding buoyancy and has numerous applications in fields such as naval architecture, fluid mechanics, and hydrology.
The discovery of Archimedes’ principle is attributed to the renowned Greek mathematician, physicist, engineer, inventor, and astronomer Archimedes of Syracuse (c. 287–212 BC). Archimedes lived in the city of Syracuse, located on the island of Sicily, which was then part of Magna Graecia, a region of southern Italy and Sicily that was heavily influenced by Greek culture.
According to the famous story, Archimedes made his discovery while taking a bath. He noticed that the water level in the tub rose as he got in, and he realized that the amount of water displaced was equal to the volume of his body that was submerged. This led him to exclaim, “Eureka!” (meaning “I have found it!” in Greek).
Archimedes’ principle is mathematically expressed as follows:
Buoyant force = Weight of the fluid displaced
Where:
 Buoyant force is the upward force exerted by the fluid on the immersed body.
 Weight of the fluid displaced is the weight of the fluid that would occupy the same volume as the immersed body.
This principle can be demonstrated through various experiments. One simple experiment involves placing a solid object, such as a rock, in a graduated cylinder filled with water. The water level will rise, and the increase in water volume will be equal to the volume of the rock. This demonstrates that the buoyant force acting on the rock is equal to the weight of the water displaced by the rock.
Archimedes’ principle has numerous practical applications. It is used in the design of ships and submarines, which must be able to float on water. The principle is also used in hydrometers, which are instruments used to measure the density of liquids. Additionally, Archimedes’ principle is applied in the field of fluid mechanics to analyze the behavior of fluids and the forces acting on objects immersed in them.
In conclusion, Archimedes’ principle was discovered by the brilliant Greek scholar Archimedes of Syracuse. This principle states that the buoyant force acting on an immersed body is equal to the weight of the fluid displaced by the body. It has significant implications in various fields and is a fundamental concept in understanding buoyancy and fluid mechanics.
How does the Archimedes’ principle apply to ships?
Archimedes’ principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces. This principle is fundamental to understanding how ships float.
How Archimedes’ Principle Applies to Ships
A ship floats because the buoyant force of the water it displaces is greater than the weight of the ship. The shape of a ship is designed to maximize the volume of water it displaces, while minimizing its weight. The hull of a ship is typically made of steel, which is a dense material. However, the hull is also hollow, which means that it displaces a large volume of water. The weight of the ship is distributed throughout the hull, so that the average density of the ship is less than the density of water. This allows the ship to float.
The amount of water that a ship displaces depends on its volume and its density. The more water a ship displaces, the greater the buoyant force will be. The denser the ship, the less water it will displace, and the smaller the buoyant force will be.
Examples of Archimedes’ Principle in Action
There are many examples of Archimedes’ principle in action in the world around us. Here are a few:
 Submarines: Submarines are able to submerge and surface by controlling their buoyancy. When a submarine wants to submerge, it takes on water, which increases its density and causes it to sink. When a submarine wants to surface, it pumps out the water, which decreases its density and causes it to rise.
 Hot air balloons: Hot air balloons float because the hot air inside the balloon is less dense than the cold air outside the balloon. The buoyant force of the hot air is greater than the weight of the balloon, so the balloon rises.
 Icebergs: Icebergs float because ice is less dense than water. The buoyant force of the water is greater than the weight of the iceberg, so the iceberg floats.
Archimedes’ principle is a fundamental principle of physics that has many applications in the real world. It is a principle that we can see at work all around us, from ships to submarines to icebergs.
Where is the Archimedes’ principle used?
Archimedes’ principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces. This principle is used in various applications, including:
1. Ships and submarines: Archimedes’ principle explains why ships float on water. The buoyant force acting on a ship is equal to the weight of the water displaced by the ship’s hull. As long as the buoyant force is greater than or equal to the weight of the ship, it will float. Submarines use ballast tanks to control their buoyancy. By adjusting the amount of water in the ballast tanks, submarines can submerge or surface.
2. Hydrometers: Hydrometers are instruments used to measure the density of liquids. They work based on Archimedes’ principle. A hydrometer floats in a liquid, and the depth to which it sinks is inversely proportional to the density of the liquid. Denser liquids cause the hydrometer to sink less, while less dense liquids cause it to sink more.
3. Hot air balloons: Hot air balloons fly because of Archimedes’ principle. The hot air inside the balloon is less dense than the cooler air outside, so it experiences an upward buoyant force. This buoyant force is greater than the weight of the balloon and its contents, causing the balloon to rise.
4. Diving: Scuba divers use buoyancy compensators (BCs) to control their buoyancy underwater. BCs are inflatable vests that divers can fill with air or water to adjust their overall density. By adjusting their buoyancy, divers can ascend, descend, or maintain a neutral buoyancy at a specific depth.
5. Fishing floats: Fishing floats are devices used to keep fishing lines suspended in the water. They work based on Archimedes’ principle. The buoyant force acting on the float is greater than its weight, causing it to float on the water’s surface. The fishing line is attached to the float, so it also stays suspended in the water.
6. Water displacement method: The water displacement method is a technique used to measure the volume of irregular objects. The object is submerged in a graduated cylinder filled with water, and the increase in water level is measured. The volume of the object is equal to the volume of water displaced.
These are just a few examples of the many applications of Archimedes’ principle. This principle is a fundamental concept in fluid mechanics and has practical uses in various fields, including engineering, physics, and everyday life.
How can the Archimedes’ Principle be used to determine the density?
Archimedes’ Principle and Density Determination
Archimedes’ Principle states that the buoyant force acting on an object submerged in a fluid is equal to the weight of the fluid displaced by the object. This principle can be used to determine the density of an object by measuring the buoyant force and the volume of the displaced fluid.
Procedure:
 Suspend the object from a string or wire so that it is completely submerged in a fluid of known density (ρf).
 Measure the weight of the object in air (Wa).
 Measure the weight of the object submerged in the fluid (Wf).
 Calculate the buoyant force acting on the object (Fb) by subtracting the weight of the object in the fluid from its weight in air: Fb = Wa  Wf.
 Calculate the volume of the displaced fluid (Vf) by dividing the buoyant force by the density of the fluid: Vf = Fb / ρf.
 Calculate the density of the object (ρo) by dividing its weight in air by the volume of the displaced fluid: ρo = Wa / Vf.
Example:
A metal block weighs 100 N in air and 80 N when submerged in water. The density of water is 1000 kg/m³.
 Fb = Wa  Wf = 100 N  80 N = 20 N
 Vf = Fb / ρf = 20 N / 1000 kg/m³ = 0.02 m³
 ρo = Wa / Vf = 100 N / 0.02 m³ = 5000 kg/m³
Therefore, the density of the metal block is 5000 kg/m³.
Applications:
Archimedes’ Principle is used in a variety of applications, including:
 Determining the density of solids, liquids, and gases
 Measuring the specific gravity of materials
 Designing and testing ships, submarines, and other marine vessels
 Calibrating hydrometers and other densitymeasuring devices
 Studying the behavior of fluids and the forces that act on them