Have you ever wondered why a tiny iron nail sinks instantly to the bottom of a bucket, but a massive cruise ship made of millions of tons of steel floats perfectly on the ocean? Or why it is so easy to lift a heavy friend inside a swimming pool? The scientific answer to all of this is Buoyancy.
The mathematical calculation of this upward force was discovered by the ancient Greek genius Archimedes. Archimedes' Principle states that the upward buoyant force is exactly equal to the weight of the water displaced (pushed out of the way) by the object.
Whenever you submerge an object in a fluid (like water or air), the fluid pushes back against the object.
Definition: The upward force exerted by a fluid on an object completely or partially immersed in it is called Buoyancy (or the Buoyant Force / Upthrust).
Because of this upward push, objects inside water feel much lighter than their actual weight on land.
It is caused by pressure differences. When a block is put in water, the water pushes against it from all sides. However, water pressure drastically increases with depth. Therefore, the water pushing up against the bottom of the block is much stronger than the water pushing down on the top of the block. This unequal pressure creates a net upward push—the Buoyant Force.
Whether an object floats or sinks depends entirely on a tug-of-war between Gravity (pulling down) and Buoyancy (pushing up).
No! Buoyancy applies to all fluids, which includes **Gases**. The only reason a Hot Air Balloon or a Helium balloon floats up into the sky is because of the buoyant force exerted by the surrounding air!
What Is a Semiconductor? — Definition, Types and Examples
A semiconductor has conductivity between a conductor and insulator. Examples: silicon, germanium. Types: intrinsic and extrinsic (n-type, p-type). Used in transistors and ICs.
What is Displacement Current? (Maxwell's Discovery)
Learn what Displacement Current is in Class 12 Physics. Understand Maxwell's correction to Ampere's Law and how a changing electric field creates a magnetic field.
What is Lateral Inversion? (Reflection of Light)
Learn what Lateral Inversion is in Physics. Discover why your left hand looks like your right hand in a plane mirror, and the science behind AMBULANCE writing.
What is a Physical Quantity? (Class 11 Physics)
Learn what a Physical Quantity is in Physics. Understand the difference between Fundamental and Derived quantities, with examples like mass, length, and velocity.
What is Reverberation? (Class 9 Physics)
Learn what Reverberation is in Sound Physics. Understand why empty rooms sound hollow, the difference between an echo and reverberation, and how to reduce it.
Turn this guide into revision flashcards, a practice exam, or an AI-generated podcast — free, no signup required.