Charlotte Miller

What Is The Cause Of Upthrust?

Are you curious to know what is the cause of upthrust? You have come to the right place as I am going to tell you everything about the cause of upthrust in a very simple explanation. Without further discussion let’s begin to know what is the cause of upthrust?

What Is The Cause Of Upthrust?

Upthrust, also known as buoyancy or buoyant force, is a fundamental concept in physics that explains why objects appear to become lighter when immersed in a fluid, like water or air. This phenomenon is a result of Archimedes’ principle, and it plays a crucial role in our understanding of fluid dynamics and the behavior of objects submerged in fluids. In this blog, we will explore the causes of upthrust and its significance in various aspects of science and everyday life.

Archimedes’ Principle: The Foundation Of Upthrust

To understand the causes of upthrust, we must first introduce Archimedes’ principle, which is the underlying concept. Archimedes, a Greek mathematician, and scientist, discovered this principle around 250 BC.

Archimedes’ principle states that “Any object, wholly or partially submerged in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object.”

This principle helps us understand the causes of upthrust and the behavior of objects immersed in a fluid.

  1. Displacement of Fluid: When an object is submerged in a fluid (liquid or gas), it displaces an amount of fluid equal to its own volume. The displaced fluid is pushed aside and exerts an upward force on the object due to the pressure difference between the top and bottom of the object.
  2. Weight and Buoyant Force: The weight of the object acts downward, and the buoyant force acts upward. If the weight of the fluid displaced (due to the object’s volume) is equal to or greater than the weight of the object, the object will experience an upward buoyant force, making it feel lighter in the fluid.

Causes Of Upthrust In Different Scenarios

  1. Floating Objects: When an object is less dense than the fluid it’s placed in, it will float. In this case, the buoyant force is greater than the object’s weight, causing it to rise in the fluid. This is why a wooden ship, for example, floats on water.
  2. Submerged Objects: If an object is denser than the fluid, it will sink. However, it still experiences an upthrust equal to the weight of the fluid it displaces. This force may not be enough to counteract the object’s weight, leading it to sink.
  3. Objects in Air: The concept of upthrust is not limited to liquids; it applies to gases as well. Objects in the atmosphere experience upthrust due to the air they displace, which is why balloons filled with helium rise in the air.

Significance Of Upthrust

Understanding upthrust and Archimedes’ principle has numerous practical applications in various fields:

  1. Naval Architecture: In ship design, knowledge of buoyancy and upthrust is essential for determining the stability and buoyancy of vessels.
  2. Aeronautics: Understanding upthrust helps in designing and controlling the lift of aircraft, balloons, and other flying objects.
  3. Submarines: Submarines use the principles of upthrust and buoyancy to control their depth in water.
  4. Construction: Architects and engineers consider buoyancy and upthrust when designing structures that may encounter buoyant forces, such as underwater structures or buildings in flood-prone areas.
  5. Scientific Research: Upthrust is a fundamental concept in fluid dynamics and plays a crucial role in various scientific studies, from oceanography to meteorology.


Upthrust, rooted in Archimedes’ principle, is a fundamental concept in the study of fluid dynamics. It explains why objects experience an apparent reduction in weight when submerged in fluids and helps scientists, engineers, and researchers design and understand the behavior of objects in various environments. The concept of upthrust, present in our everyday lives and the natural world, continues to be a cornerstone of scientific exploration and technological advancement.


Is Upthrust Caused By Gravity?

The upthrust is considered to act at the center of buoyant i.e., the center of gravity of the displaced fluid.

What Is Upthrust Class 9th?

When a body is immersed in a fluid, it experiences an upward force which is called upthrust or buoyant force. Its SI unit is newton.

What Is The Cause Of Buoyancy Class 9?

What causes buoyancy? The pressure exerted by the fluid in which the object is immersed causes buoyancy. Also, the buoyant force experienced by the object is always upwards because the pressure of the fluid increases with the depth.

What Is The Condition Of Upthrust?

According to Archimedes’ principle, ‘If a body is completely or partially immersed in a fluid, then it experiences an upwards force or an upthrust, which results in an apparent loss of weight equal to the weight of the fluid displaced by the body. ‘ It is the first condition of equilibrium.

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