Solids are often very dense -
have a high mass for a certain
volume
Unit: kg/m cubed
grams/cm cubed
Example: A piece of iron has a
mass of 390 kg and a volume of
0.05 metres cubed. What is its
density
390kg / 0.05 metres cubed
= 7800 kg/m cubed
The volume of a regular object can be
calculated by multiplying its length x
width x height
Irregular: Using a displacement
can and a measuring cylinder
Displacement:
Find the initial water level: 60
milliliters or 60 cm cubed
Put the object in the water and find the
FINAL water level: 72 milliliters or 72
cm cubed
Volume of cylinder = Final - initial = 12 cm3
Pressure under a solid
Pressure (in Pascals) = Force (in
Newtons) / Area (in square meters
Pressure in Liquids
and Gases
Magdeburg Hemispheres
2 large bowls put together and then pumped the air
out. The bowls could not be pulled apart, even when
attached two teams of horses to the bowls.
Pressure and Depth
The force at the bottom of the column is equal to all the weight of water above it. The volume
(V) can be found by multiplying the area of its base (A) by the height (h) of the column.
The mass can be worked out by multiplying the volume by the density (p)
Volume = Area of Base x Height of Column
Mass = Volume x Density
Density = Mass / Volume
The force (F) on the bottom is equal to the weight of
this volume of water = which is mass x 10
Pressure Difference (in Pascals) = Height (in m) x Density (in kg/m3) x g (in N/kg)