Have you ever looked across MOA, well before they filled it up with soil, and seen the ships on Manila Bay? Have you ever wondered why that ship floats? And then ask your self will this keychain on my hand float like that ship? Well if you tried answering the question by throwing your keychain into the ocean, I am guessing you are now in line at a Mr. Quickie shop replacing the keys you lost, that is if you had an original stored somewhere. If not, well it is a key maker you will need then. All these would not happen if you understood buoyancy.
Because if you are familiar with Buoyancy, you would know that your keychain will sink, unlike that ship that displaces water weighing more than its own weight.
Your keychain obviously is lighter than that ship and takes out lesser water. This is buoyancy.
It is the upward force exerted on any object placed in liquid or gas.
In scuba diving, you add air to your BCD or put on more weight around your body to be able to stay buoyant less buoyant, and more buoyant to counter the water displaced.
Let’s look at the meaning of Displace.
Whether the object is round, pointed, or square, it pushes out water when it is placed on water. That water pushed out is the volume. Volume is the space occupied by the object. And when you push out water in place of the object then you are displacing it with that object’s own volume.
Try to recall going into a swimming pool. You go in and some water goes out into a drain by the side of the pool in place of your body that just entered the pool. If you measured that amount of water, you will definitely see if you displaced water equal, lesser, or more which will explain why you floated or sank.
Archimedes said, “ An object placed in water is buoyed up by a force equal to the weight of the quantity of water it displaces.”
A 10-centimeter by 10-centimeter by 10-centimeter wooden cube displaced 350 ml of water so it is less than 1000 cc or 1 Liter of water.
Now let’s compare it to an aluminum block with the exact dimensions. Because it is heavier, it displaces more than 1000ml or 1 liter that weighs 1 kg, the aluminum block sinks because it weighs more than the water it displaces.
Or to put it simply:
—If an object displaces an amount of water weighing more than its own weight, it will float.
—If an object displaces an amount of water weighing less than its own weight, it will sink.
—If an object displaces an amount of water weighing equal to its own weight, it will neither
Neither float nor sink but remain suspended in the water.
If an object floats we call it —positively buoyant
If an object sinks we call it —negatively buoyant
If it neither floats nor sink —it is neutrally buoyant