Archimedes Principle

-An object submerged in a fluid experiences a buoyant force equal to the weight of the fluid it Displaces."

What it Means:

-When an object is placed in water (or any fluid), it pushes some of the fluid out of the way - this is called dispicacement.

-The fluid then pushes back on the object with an upward force called buoyant force.

-The strength of this upward push equals the weight of the fluid that was displaced. This is why some objects float and others sink.

Buoyant Force

The buoyant force is the upward force exerted by a fluid on an object placed in it. This force acts against gravity.

Key Idea:

-The more fluid an object displaces, the greater the buoyant force

Example

-When you drop a piece of wood in water, it floats because the buoyant force pushing up is greater than or equal to the wood's weight.

Displacement

-Displacement refers to the volume of fluid pushed aside when an object is placed in it.

Example:

-When you step into a full bathtub, water spills out that's displacement.

-A rock dropped into water pushes some water out of the way, the heavier the rock, the more water it displaces

APPARENT WEIGHT LOSS IN WATER

-Objects feel lighter in water because the buoyant force reduces the effect of gravity. on them. This is called apparent weight loss.

Example:

-If you try to lift a stone underwater, it feels easier than lifting it on land. That's because the water is helping you lift it by pushing up on it.

Summary

-A floating object: Boyant force = Object's weight

-A sinking object: Buoyant force < Object's weight