Buoyancy

Water exerts a force called the buoyant force Water exerts a force called the buoyant force. This force acts upward (against gravity) on submerged objects. That’s why you could lift a huge amount of weight underwater that you would never dream of lifting on land! You would be “helped” by this force Why “UP”? Because pressure increases with depth, the force acting on the bottom of a submerged object is always greater the force on the top. The imbalance creates an upward net force.

(How bad does it want to go “Up”?) Just what is it that determines how much buoyant force is acting on an object? (How bad does it want to go “Up”?) Which is easier to push down below the water surface – a beach ball or a ping pong ball? Of course you know it would be the ping pong ball but why? As a object’s volume increases, so does the amount of water it displaces. Archemides’ principle states that the buoyant force on an object is equal to the weight of the fluid displaced by the object..

How does this relate to DENSITY? Buoyancy and Density Again, Archemides’ principle states that the buoyant force on an object is equal to the weight of the fluid displaced by the object. Therefore, a change in either the object’s volume or the weight of the fluid that object displaces can alter buoyant force. If an object is denser than the liquid it’s in, it will sink. Less dense, and it will float. When it sinks, gravity (weight) is winning. When it floats, the buoyant force wins! How does this relate to DENSITY? If an object weighs more than the same volume of water it takes up, it’s said to be denser than water and sinks. If the volume of water the object displaces would weight more than that object, it is less dense.