Upthrust, also known as buoyant force or buoyancy, refers to the upward force exerted by a fluid on an object immersed in it. It is a fundamental concept in fluid mechanics and plays a crucial role in various natural phenomena, such as the floating of objects on water and the behavior of submarines and hot air balloons.
When an object is submerged in a fluid, such as a liquid or a gas, it experiences an upward force due to the pressure difference between its upper and lower surfaces. This force is equal to the weight of the fluid displaced by the object. According to Archimedes’ principle, this buoyant force is proportional to the volume of the displaced fluid and acts in the opposite direction to gravity.
Upthrust = Weight of fluid displaced by the object
The magnitude of the upthrust depends on the density of the fluid and the volume of the object. If the density of the object is greater than that of the fluid, it will sink as the upthrust is less than its weight. Conversely, if the density of the object is less than that of the fluid, it will float as the upthrust exceeds its weight. When an object is partially submerged, it experiences an upthrust equal to the weight of the fluid displaced by its submerged portion.
The concept of upthrust has significant applications in engineering and everyday life. It is utilized in designing ships and submarines to ensure their buoyancy and stability. It also explains why certain objects float or sink in liquids and gases.
