Here's why:
* Buoyancy: An object floats when the buoyant force acting on it is greater than or equal to the object's weight.
* Buoyant Force: The buoyant force is the upward force exerted by a fluid (like water) on an object submerged in it. This force is equal to the weight of the fluid displaced by the object.
* Density and Buoyancy: For an object to displace enough water to create a buoyant force equal to its weight (and thus float), it needs to be less dense than the water. This means the object has a lower mass per unit volume compared to water.
In simpler terms:
Imagine a block of wood floating in water. The wood displaces a volume of water that weighs the same as the wood itself. If the wood were denser than water, it would displace less water (by volume) and wouldn't be able to create enough buoyant force to support its weight.
