Download Archimedes` Principle

Buoyancy is the force exerted on an object
by a fluid and is usually acts against gravity.
This is why objects feel lighter in water.
Some of the force of gravity (weight) is
cancelled out by the force of buoyancy. If
the buoyant force is stronger than the force
of gravity, the object will float in the fluid.
Gravity
Buoyant Force
Archimedes’ Principle states that the
buoyant force of a fluid is equaled to the
weight of the fluid displaced by the object. If
an object can displace (push away) enough
fluid to equal its weight, it will float. This is
why a tremendous ship made of iron can
float but a cannonball would sink. The ship’s
shape allows it to push enough water away
to equal the weight of the ship.
5.0
Pounds
If the object can push
away an equal weight of
fluid as its own weight, it
will float in that fluid.
0.0 lbs
5.0
10.0
Pounds
If the object pushes away
a lower weight of the fluid
than its own weight, it will
sink in that fluid.
0.0 lbs
6.0
The amount of water that was displaced by the
floating boat weights the same as the boat itself.
According to Archimedes’ Principle, this is why
the boat floats and doesn’t sink.
Displaced Water
If the rock is thrown overboard, how will the
water level in the tub change?
Sinkable
Rock
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