🌊 Why do some things float and others sink?

Some things float because they are light like a feather 🪶 or a balloon 🎈. Others sink because they are heavy like a rock 🪨 or a toy car 🚗. When you put something in water, the water tries to hold it up. If the thing is too heavy, it sinks! 🌊

Try this: Drop a leaf 🍃 and a coin 💰 in water. The leaf floats, but the coin sinks!

Things float or sink because of density and buoyancy! 🌊

Density means how much "stuff" is packed into an object. A cork � floats because it’s less dense than water. A metal spoon 🥄 sinks because it’s denser.

Buoyancy is the water’s upward push. If an object’s weight is less than the water it displaces (pushes aside), it floats! Ships float because their shape displaces a lot of water.

Floating and sinking depend on Archimedes’ Principle: an object in fluid experiences an upward force equal to the weight of the displaced fluid. Here’s how it works:

• Density (mass/volume): If an object’s density is less than water’s (1 g/cm³), it floats. Wood (0.6 g/cm³) floats; iron (7.9 g/cm³) sinks.
• Buoyancy: Hollow objects (like ships) displace more water than their weight, so they float despite being heavy.

Saltwater is denser than freshwater, making floating easier (e.g., the Dead Sea).