3B Scientific Air Cushion Plate - Manual (Page 32)

Physical Experiments on the Air-Cushion Table
32
The larger the mean velocity of the hover discs
is, the faster individual discs will leave the origi-
nal section.
Interpretation:
A liquid contains molecules of different veloci-
ties at all times. The fastest among these mole-
cules succeed in leaving the liquid. This process
of evaporation also occurs beneath the boiling
temperature of the liquid. Since molecules from
the gas atmosphere also return into the liquid, a
dynamic equilibrium state is soon reached.
The speed of evaporation increases as the tem-
perature rises.
Note:
The inclination of the experiment surface simu-
lates the gravitational field. This makes more par-
ticles return from the gas phase into the liquid
phase.
2.2.6 Liquefaction of a Gas through Pressure
Components:
Air-cushion table with fan
Overhead projector
Magnetic barrier, long
2 Pieces
Magnetic barrier, short 2 Pieces
Magnetic piston 1 Piece
Guide piece for the
magnetic piston
l Piece
Hover disc, red 20 Pieces
Model simulation
Real Object Model
Vessel containing Experiment surface of
the liquid the air-cushion table
Walls of the vessel Magnetic barriers
Piston for the com- Magnetic piston
pression of the gas
Gas molecules
Hover discs
How to proceed:
Align the air-cushion table horizontally and at-
tach the magnetic barriers. Place the piston on
the experiment surface right next to barrier no. 2.
The guide piece for the magnetic piston placed
onto magnetic barrier no. 2 ensures excellent
guidance of the piston rod. Arrange the magnetic
hover discs near barrier no.1.
Turn the fan to a medium setting. Slowly move
the piston towards barrier no.1 until the avail-
able area for the hover discs is less than half of
the experiment surface. Observe the configura-
tion and motions of the hover discs.
Result:
Reducing the area in size changes the behavior
of the hover discs. The number of impacts in-
creases. The distances in which the hover discs
can move in a straight line become shorter and
shorter. Oscillating and circular motions prevail.
Permanent changes in location mostly occur as a
mutual exchange of positions.
Interpretation:
Under certain conditions, the compression of a
gas can result in liquefaction. The configuration
of the molecules and their type of motion change
in this process. While in the gaseous aggrega-
tion state only translational movements occur, the
motion prevailing in the liquid state is oscilla-
tion around the respective location.
2.2.7 Solidification of a Liquid
Components:
Air-cushion table with fan
Overhead projector
Magnetic barrier, long
2 Pieces
Magnetic barrier, short 2 Pieces
Air-cushion table with fan
Overhead projector
Magnetic barrier, long
2 Pieces
Magnetic barrier, short 2 Pieces
Hover disc, orange 25 Pieces
Model simulation
Real Object Model
Vessel containing Experiment surface of
the liquid the air-cushion table
Walls of the vessel Magnetic barriers
Molecules of the Hover discs
liquid
How to proceed:
Align the air-cushion table horizontally and at-