Density Created by Dr. A. Davila 2010

Three Cubes of Three Different Types of Woods

Balance Scale

Pine Verses the Oak

Pine Verses the Poplar

gram (g) gramo (g) A unit for mass Una unidad de masa 1 gram = 0.35 ounces = 1 gram = 5 grams

Use the Triple-Beam Balance to measure mass (g)

Calibrate your Balance if the pointer is not centered on zero

Start by making sure the riders are on the zero setting

Turn Knob to right or left

Place your mass to be measured in the center of the clean pan. Slide the riders from slot to slot until the pointer is centered back at zero

If not enough, move the next largest unit rider

Add together the beam positions of all three riders. This will be the mass of the object measured.

The oak cube has a mass of 13 grams

liter (L) litro (L) A unit measuring volume or capacity Una unidad de volúmen o capacidad 1000 mL = 1 L mL = 1 qt. meniscus

200 milliliters of water

Displacement of the water due to the cub How much water got displaced?

Displacement of the water due to the cube. How much water got displaced? 225

About 14.5 mL 225

Length width height VOLUME V = 1 cm V = 1 in 3 C C

milliliter (mL) millilitro (mL) A fraction of a liter (1/1000 L) 1 cubic centimeter is equal 1 milliliter Una fracción de un litro (1/1000 L) Un centimetro cubico es igual que 1 millilitro 1 cm 3 = 1 mL (cc)

milliliter (mL) millilitro (mL) A fraction of a liter (1/1000 L) 1 cubic centimeter is equal 1 milliliter Una fracción de un litro (1/1000 L) Un centimetro cubico es igual que 1 millilitro 1 cm 3 = 1 mL (cc)

The oak cube has a mass of 13 grams and a volume of 16.5 milliliters 13 g 16.5 mL D= 0.77 g/mL D=

Real World Application Density can be used to compute the weight of a piece of machinery or part of a bridge or building before it is actually constructed. An engineer needs only to know the volume and density of the material of which it is to be made. The engineer can compute beforehand the load that each part of the structure will have to support. This will determine whether the design is of sufficient enough. mVmV D=

Real World Application Density can also be used to differentiate a pure metal from an alloy, as in the classic case where Archimedes had to determine if Sicilys king had a crown of pure gold or an alloy.

What Archimedes Measured Weight of the gold that Hiero had given the jeweler) Volume of water the gold displaced Weight of the crown Volume of the water the crown displaced

What Archimedes Found Archimedes found that the jewelers crown displaced more water than the gold block. Archimedes Argument (Explanation) Archimedes reasoned that a gold crown should displace the same volume of water as the as the gold Hiero had given the jeweler. However, if it was not pure gold, but a silver alloy as the king suspected, that would increase the volume of the crown and displace more water.

He observed that the jewelers crown displaced twice the volume of water displaced by the gold and concluded that the jewelers crown was not made from gold. Because gold weighs more than silver, he reasons that a crown mixed with silver would have to be bulkier to reach the same weight as one composed only of gold; therefore it would displace more water than its pure gold counterpart.

Thus, Archimedes showed that water displacement was a good method for measuring the volume of irregular objects (as Archimedes certainly was!). An object immersed in water will displace a volume of water equal to the volume of that object.