Archimedes Principle

Key Notes:

Definition of Archimedes’ Principle:

• Archimedes’ Principle states that when an object is fully or partially immersed in a fluid, it experiences an upward force called buoyant force. This force is equal to the weight of the fluid displaced by the object.

Buoyant Force:

• The buoyant force is the reason why objects either float or sink in a fluid.
• It acts in the opposite direction to gravity, making objects feel lighter when submerged.

Displacement of Fluid:

• The amount of fluid displaced depends on the volume of the submerged part of the object.
• If the object is fully submerged, it displaces a volume of fluid equal to its own volume.

Floating and Sinking:

• An object floats if its weight is less than or equal to the buoyant force (i.e., the weight of the displaced fluid).
• An object sinks if its weight is greater than the buoyant force.

Relation to Density:

• The principle relates to the density of the object and the fluid.
• If an object’s density is less than the fluid’s density, it will float; if it is more, it will sink.

Formula:

• Buoyant force (F_b) = weight of displaced fluid = mass of displaced fluid × gravitational acceleration.
• F_b = ρ_fluid × V_displaced × g, where:
  • ρ_fluid is the fluid’s density,
  • V_displaced is the displaced volume of the fluid,
  • g is the acceleration due to gravity.

Applications of Archimedes’ Principle:

• It is used in designing ships and submarines, determining the density of objects, and in hydrometers to measure the density of liquids.

Archimedes’ Discovery:

• According to legend, Archimedes discovered this principle while taking a bath and realized that the water displaced by his body was proportional to the volume of his body.

Let’s practice!