Discover the forces at work underwater, which dictate why large boats float but small pebbles sink.
- The buoyant force is an upward-acting force determined by the weight of the displaced water.
- Ships float because they are hollow and have a large buoyant force.
- Density is the amount of mass in a set volume.
- An object will float if its density is less than the buoyant force.
Huge metal ships can float across the sea yet smaller, lighter objects sink.
Why is this?
We know that gravity pulls objects downwards.
The force is known as weight.
But underwater there's another, upward force, called buoyancy.
If the weight of an object is greater than the buoyant force, the object will sink.
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