Buoyancy

Buoyancy • A solid body submerged in a liquid or a gas weighs less than when weighed in free space. This is because of the upward force, called buoyant force, which any fluid exerts on a body submerged in it.
• An object will float if this the upward force of the fluid is greater than the weight of the object.
• Objects denser than the fluid, even though they sink readily, appear to lose a part of their weight when submerged.
•  A person can lift a larger weight under water than he or she can possibly lift in the air.
•   The overflow can is filled to the spout with water. The heavy metal cube is first weighed in still air and weighs 10 lb. It is then weighed while completely submerged in the water and it weighs 3 lb.
•  The difference between the two weights is the buoyant force of the water. As the cube is lowered into the overflow can, the water is caught in the catch bucket.
•  The volume of water that overflows equals the volume of the cube. The volume of irregular shaped objects can also be measured by using this method.
• If this experiment is performed carefully, the weight of the water displaced by the metal cube exactly equals the buoyant force of the water, which the scale shows to be 7 lb.