🌊 FLOATING & SINKING: BUOYANCY
PAGE 1 OF 5 · WHY STEEL CAN SINK OR FLOAT
WATER GIVES A LIFT
WATER AND AIR ARE ALWAYS PUSHING
Here is a puzzle. A tiny bit of steel goes plink and drops to the bottom. The same kind of steel is used to make a big ship, and the ship stays up! The steel is still steel. What changed? The shape changed. A wide hull shoves a lot of water out of the way. A little bolt shoves out only a tiny bit.
When you put something in water (or in air, because air works too), the water pushes on every part it touches. A little deeper, the water squeeze is a bit stronger. So the bottom of the object gets a bigger upward push than the top gets a downward push. All that together makes an upward push we call buoyancy (some people say upthrust too). If the upward push and the weight match, the thing floats. If the weight wins, the thing sinks. If the push and weight match just right, the thing can hang in the water without going up or down.
When you put something in water (or in air, because air works too), the water pushes on every part it touches. A little deeper, the water squeeze is a bit stronger. So the bottom of the object gets a bigger upward push than the top gets a downward push. All that together makes an upward push we call buoyancy (some people say upthrust too). If the upward push and the weight match, the thing floats. If the weight wins, the thing sinks. If the push and weight match just right, the thing can hang in the water without going up or down.
Think of it like a friendly game. The water cannot push on you if you are not in the water, but when you are in, it always has something to say.
LIFT!
SMALL BIT VS BIG SHIP
🪨 A little lump is heavy for its size, so the water it moves is small
🚐 A wide ship moves a big part of the ocean out of the way
📈 Gravity pulls you down, buoyancy pokes you up
✅ The question is: does the weight of the moved water help enough?
🚐 A wide ship moves a big part of the ocean out of the way
📈 Gravity pulls you down, buoyancy pokes you up
✅ The question is: does the weight of the moved water help enough?
BALLOONS IN THE SKY
🎈 A helium balloon floats up in the sky
💨 Air acts like a fluid too, not just water
📈 The balloon moves air out of the way, just like a boat moves water
🌈 If the upward push from the air beats the weight, you go up, up, up
💨 Air acts like a fluid too, not just water
📈 The balloon moves air out of the way, just like a boat moves water
🌈 If the upward push from the air beats the weight, you go up, up, up