Buoyancy

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To determine density we use volume and mass. Now he could determine the density of the crown. He found that the crown was a mixture of gold and silver and that the goldsmith had tried to cheat the king.

The crown and the gold nugget have equal weight

The crown displaces more water than the gold nugget

Slide 13

Archimedes did other experiments with buoyancy and fluids.

In object immersed in a fluid does not rise or sink if the amount of force pulling down (gravity) equals the amount of force pushing up (buoyancy).

Slide 14

Neutral buoyancy – when gravity equals buoyancy.

Archimedes’ principle – the buoyant force acting on an object equals the weight (force of gravity) of the fluid displaced by the object.

Slide 15

How Buoyancy and Density are Related

Buoyant forces depend on density. The more dense a fluid the more easily an object will float in it. If fluids have a different density the less dense one will float on the denser one.

Slide 16

Which is more dense, water or oil?

Water

Slide 17

Hydrometer – used to measure the density of a liquid

Slide 18

Where would a hydrometer be used?

- determine if the antifreeze in a car is of the right mixture

- determine the sugar content of canned fruit syrup

content of alcohol in wine