The reason a cork floats while a nail sinks is due to differences in density.

• Density Defined: Density is the mass per unit volume of a substance. In simpler terms, it's how much "stuff" is packed into a certain amount of space.
• Buoyancy: Whether an object floats or sinks depends on the buoyant force acting on it and the object's weight. Buoyant force is the upward force exerted by a fluid that opposes the weight of an immersed object. If the buoyant force is greater than the object's weight, the object floats.
• How Density Affects Buoyancy: An object will float if it is less dense than the fluid it is placed in. If it's denser, it will sink.

Cork vs. Nail:

• Cork: Cork is much less dense than water. This is because it contains many air pockets. Because cork is less dense than water, it experiences a buoyant force greater than its weight, causing it to float.
• Nail: A nail, typically made of metal like iron or steel, is much denser than water. For the same volume, a nail contains significantly more mass than water. Because the nail is more dense than water, the buoyant force is less than its weight, causing it to sink.

In summary, the floating or sinking of an object depends on whether it is more or less dense than water.