Density

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Simple Density Demonstration.


Density is a physical property of matter.
It is the amount of substance (mass) per unit volume. Dimensionally [M][L]-3


Equipment.


Three glass containers, large enough to accommodate the objects that are used so they don’t catch on the sides. Also they should be large for the class to see.

  • Ethanol
  • Water
  • Golden Syrup/Honey
  • Large ice cubes
  • Wax cubes
  • Golf balls
  • Perspex
  • Tongs


Density Information.

All values are approximate.

Density is calculated by dividing mass by volume.

Ethanol - 790 kg/m³

Water @ 20°c –1000kg/m³

Golden syrup - 1500kg/m³

Honey –1420kg/m³

Ice assuming 0°c – 916kg/m³

Candle wax – 930kg/m³

Golf balls – 1150kgm/³

Perspex – 1190kg/m³


Method.

Each beaker is half filled with one of the liquids. The depth should be sufficient to float the objects, but not enough to overflow when the objects are added.

The ice cubes will float in the water but sink in the ethanol, as will the wax cubes. The Perspex and the golf balls will sink in the water but float in the golden syrup.


Number crunching!

Less dense fluids/objects float on more dense fluids if they do not mix. So the smaller the number – and the greater the difference in the numbers - the more likely it is to float on a fluid with a higher number.

Density is an important concept regarding buoyancy. The ability of an object to "float" when it is placed in a fluid is called buoyant force.

Increasing the amount of a substance does not increase its density; rather it increases its mass.


Notes.

We’ve Archimedes and a gold crown to thank for giving us the concept of density, plus a ‘eureka’ moment. Look him up! wikipedia link

Wax cubes are made by carefully pouring melted candle wax, wicks removed, into moulds.

It’s more impressive if the objects ‘floated’ are the same size.


--K4thie 16:33, 23 January 2011 (UTC)

See also Density Ladder

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