All posts by Javid Khan

Mr.Javid Khan.J is the Founder & CEO of this blog 'The Secrets of Science'. He is an Aeronautical Engineer who aspires to become an Astronaut. He is interested in learning new things each day, expanding his horizon of knowledge in every aspect .He is fond of knowing the science behind everyday life and wish to share them to the world.

Buoyancy and Archimedes Principle

Buoyancy and Archimedes Principle
Buoyancy and Archimedes Principle

Buoyancy-One such frequent word we all have come through in our science book since school days with a funny “bath tub” history. Generally speaking buoyancy is the ability to float. Well, more answers & explanation to this (buoyancy) can be found out in the Archimedes principle of floatation and that’s exactly what this article is all about. So, read on…

Eureka Moment!

It’s because of Greek mathematician and inventor Archimedes that we knew why some things float & some don’t. We all would have been familiar about the oldest and well known tale which revolved around Archimedes legendary “Eureka!” moment when he realized the principle of buoyancy while taking a bath. He observed that his body displaced (pushed out a place) a certain volume (amount of space a material occupies) of water from the tub.

“Staying Afloat”- Archimedes Law:

His principle states that fluids, such as air or water, apply an upward buoyant force on objects that are partially or totally submerged in the fluids. Such object are said to have buoyancy (the tendency to float when placed in a fluid). It also states that the magnitude of buoyancy force is equal to the weight of the fluid displaced.

Whether a material floats or sinks in a fluid doesn’t depend on its weight but rather on its density. An object with a density greater than the fluid sinks, while an object with a density less than the fluid floats.

Fun time:

For easy understanding I will explain it with a simple experiment which you can try at home at no cost.

 Take a vessel or container full of water & just drop a plastic ball into it. You will notice that the ball will float because of its lighter density. When you try to push the ball into the water you would have noticed that some of the water has been spilled from the vessel. That spillage is due to the immersion of the ball into the container .Explaining from the scientific point of view   ”the volume of the water spilled is equal to the volume of object (ball) immersed”.

Here I wish to pose you a question. ”What happens if the same ball is released in the air?” Definitely it will take its path towards the ground because the ball has greater density than air. But in case of water the same doesn’t happens. When the ball is dropped into the water, the ball experiences an upward force which pushes the ball to the surface of the water. That upward force is called upthrust or buoyant force or Archimedes force.

How Buoyant Force acts?

We all know that pressure decreases when altitude increases. This change in pressure with altitude is the effect of gravitational force. When an object is immersed, top surface of the object has less pressure than the bottom surface. This pressure difference creates the upward force called buoyant force. The magnitude of this force depends on the difference in pressure between the top and bottom surface of the object.

Applications of Buoyancy:

Whatever we learn is indeed connected to our real life. The practical applications of Archimedes principle are follows:

-Common example of buoyancy is the moment when you feel lighter in a swimming pool and it’s because the water is pushing up on your body.

-Life jacket is one such example where buoyancy can be experienced & makes us to afloat in water.

-Ships at sea, submarine airships such as balloons, fishes use Archimedes principle.