R
Air Track Rail
Air Track Rail, Basic Equipment
1 PURPOSE AND CHARACTERISTICS
With its extremely low friction the set of equipment, Air
Track Rail 11202.77, is ideally suitable for investigating kinematic and dynamic behaviour in straight line motion. The
main component in this system of equipment is the 2m long
Air Track Rail 11202.17 on which numerous experiments
can be carried out with the aid of the separate parts included with 11202.77. The relationship between displacement, time, velocity and acceleration as well as the dynamic
coupling of these quantities can be determined in impressive experiments.
Supplementary electronic measurement equipment (light
barriers, electronic timers, computer-aided measurement
acquisition systems) are needed for the time measurement.
2 DESCRIPTION
The Air Track Rail Basic Equipment 11202.77 consists of
the following individual parts.
1 Air Track Rail 11202.17
The track is formed by a 2m long aluminium tube with
a square cross-sectional shape (63mm 3 63mm). The
track is terminated at the end of the tube; the end face
at the start of the track has an opening (d = 40mm) for
connecting a Blower 13770.93 via the Pressure Tube
11205.01. The two gliding surfaces each have two rows
of holes which are displaced with respect to one another; hole diameter 1mm, separation 20mm. An air cushion is formed under the gliders which are positioned
on the track by the emitted compressed air, so that the
gliders can glide along the track with almost no friction.
For the measurement of the length the two gliding surfaces have two scales running in opposite directions
with mm divisions and cm figures.
Two knurled screws are fitted at the ends of the track,
enabling the track to be fitted to the end-holders included with 11202.77; they should be used in this position
provided the experimental objective does not require a
different arrangement.
The square tube rests on a U-section carrier rail which
is supported on the experiment bench with its feet in a
three-point arrangement; two adjustment screws provide the horizontal alignment of the track. The square
pipe and carrier rail are joined with seven screws which
have been used to adjust the track as supplied exworks (basic adjustment). Since the screws on the bottom of the rail are accessible, a track which has been
thrown out of adjustment by improper handling can be
readjusted by the user, see 3.4. However, unless there
is a compelling reason, the screws should not be altered.
2 End-Holder for Air Track Rail 11202.15
(two included)
These are attached to the air track rail at the ends of the
track using the appropriate knurled screws.
Note: If the mechanical starting system is used, consisting of items 11202.13 and 11202.14 (not included in
11202.77), then the starting system is fastened to the
air track rail instead of an end-holder.
3 Glider 11202.02
(two included)
Roof-shaped, 130mm long, black anodised aluminium
profile section for placing on the track. A ridge strip with
five 4mm sockets enables screens and other plug-in
elements to be fitted.
The mass of the glider itself is approximately 170g; with
fitted screen, l = 100mm and two plug-in elements the
mass increases to a total of about 200g. Scales are
PHYWE SYSTEME GMBH · Robert-Bosch-Breite 10 ·D-37079 · Göttingen · Telefon (0551) 604-0 ·Telefax
(05 51)60 41 07
11202.17
11202.77
Operating Instructions
or the Plate with Plug 11202.10. It is recommended that
the plug-in elements are fitted to the lower holes in the
gliders, because with the elastic collision a small torque
affects the gliders and energy losses are thus minimised.
6 Rubber Band 11202.09
(10 pcs) for clamping in the pair of grooves in the fork
11202.08.
7 Plate with Plug 11202.10
For plugging (with vertical plate) on the end face of the
glider. The plate forms the opposing element to the
Fork 11202.08 during the elastic collision.
8 Tube with Plug 11202.05
9 Needle with Plug 11202.05
For an inelastic collision the plug-in elements are plugged onto the two opposing end faces of the gliders (it is
recommended that the lower holes are used). During
the collision the needle penetrates the plasticine filling
of the tube, firmly coupling both gliders together. The
plug combination of the tube and needle can also be
used to retain a glider at the end holder after its movement has taken place.
Please refer to the list of equipment for other parts needed
to conduct experiments.
3 INITIAL OPERATION AND HANDLING
3.1 General remarks
Before the air track rail is operated, an End-Holder
11202.15 should be fastened to the end of the track with the
two knurled screws. Normally, an end-holder is also atta-
needed to find the exact weight. To increase the mass
to 300g or 400g, 50g Slotted Weights (02206.01) can
be placed on the two steel pins and evenly distributed
on both sides for reasons of symmetry. Also for this reason, both end faces should always be fitted with a plugin element even when only one is needed.
4 Screen 11202.03
Screen 11202.04
(two of each included)
The black plastic screens are plugged onto the ridge
strip of the glider with their 4mm plugs. They are used
to control timing instruments (e.g. Electronic Digital
Counter, 6 decade (13603.93), 4 decade (13600.93))
through light barriers fitted to the track. The two 50mm
high screens differ in their length and mass:
Screen Length Mass
11202.03 100mm ± 0.2mm 10g ± 1g
11202.04 25mm ± 0.1mm 5g ± 0.5g
Plug-in elements
The plug-in elements listed below (with 4mm plug) all
have the same mass (10 g ±1 g) and the same position
for the centre of gravity, so that the glider is symmetrically loaded when both end faces are fitted with a plugin element.
5 Fork with Plug 11202.08
With four pairs of grooves for clamping a rubber band
from 11202.09. The rubber band must not sag, but
should not be under strong tension.
The fork with rubber band is used for the elastic collision. Two gliders are fitted on facing ends with the fork
11202.17
2
10
22
11
4
25
5
18
23
19
1
2
7
15
8
9
5
6
17
21
20
12
16
13
14
3
24
26
27
ched to the start of the track (the end with the pressure tube
connection), unless the mechanical starting system
(11202.13 + 11202.14) (not included in 11202.77) is used.
In this case it is fitted instead of the end-holder.
The air track rail is set up on a flat surface that is as level as
possible and connected to the blower using the pressure
tube. The blower pressure should be set such that the gliders just reliably elevate from the track and are freely supported on the air cushion; depending on the glider load this
can be at different pressures. A blower pressure that is too
high should be avoided, because it impairs the steady positioning of the glider.
The track, which itself has been adjusted at the works, must
be aligned as level as possible with the two adjustment screws on the base of the carrier rail. This can be initially carried out by eye or using a spirit level; accurate alignment
must be obtained with the blower operating and by setting
a glider on the track. With a properly levelled track there
should be no or very little glider acceleration ; a slight pendulum movement caused by the air current is unavoidable.
This test should be conducted on various points on the
track. The action of external forces, e.g. due to vibration or
draughts should be avoided.
3.2 Electronic timing
The electronic digital counters mentioned in the list of
equipment are suitable for the time measurement. One or
two light barriers can be connected to these devices for electro-optical control. The light barriers must be arranged at
the required point on the track so that the screen on the glider interrupts the beam of light between the light source and
the photoelectric sensor when it passes. A holder made
from stand-support components is suitable. A ruler with gliders can be attached to the holding structure to demonstrate the length measurement.
3.3 Producing constant acceleration
The glider should be fitted with the Hook (11202.07*). To
produce the acceleration, a Silk Thread (02412.00*) to the
end of which a Weight Holder (02407.00*) is attached, is
passed over a low-friction Precision Pulley (11201.02*).
One or more 1g Slotted Weights (03916.00*) are placed on
the holder; up to 20g is permissible for the pulley.
Since the nominal mass of the glider (200g for the glider
with 100mm screen and two plug-in elements) is subject to
a certain tolerance, weighing should be carried out to exactly determine the accelerated mass and supplementary
weights used if required. Also, the mass of the weight holder (1g) and the 1g slotted weights used must be taken into
account as an additional corrective quantity; an equivalent
mass for the rotating pulley can be taken as 2.2g.
* not included in 11202.77.
3.4 Readjusting the air track rail
A feature of the Air Track Rail 11202.17 is that it can be readjusted with regard to the straightness of its longitudinal
profile. Correction of the basic ex-works adjustment is however only necessary it the straightness has become impaired due to mechanical stressing of the track.
The adjustment procedure demands a certain amount of
manual skill as well as a systematic method of working and
assuming this, it can be carried out by the user. Seven Allen
screws accessible on the bottom of the carrier rail are to be
adjusted where required. A normal Allen key, 5mm AF, is
needed to adjust these M6 screws (pitch 1mm/turn). Generally for readjustment, an adjustment of only up to one half
turn of the screw is required which must be taken in stages
and the track straightness should be tested at each stage.
By turning the screw clockwise the square tube is pulled downwards in the vicinity of the screw and it is raised when the
screw is turned in the opposite direction.
The longitudinal straightness of the track section should at
least be determined qualitatively before the adjusting screws are adjusted. This is done with the blower operating
and with the aid of a glider put on the air track rail. First the
track should be aligned with it level at the centre. Then the
glider is positioned at various points along the track and the
direction and approximate magnitude of the acceleration
occurring at that point is found. (If an estimate is not regarded as being sufficient, the time t for the glider to move from
its starting point over a distance s can be determined. The
acceleration is then a = 2 s/t
2
). The magnitude is a measure
of the gradient of the track at the test point.
It is essential that external force affects, such as draughts,
are avoided during the test.
The qualitative straightness of the track can be found from
the results and, as an aid, can be drawn out. It may be, for
example, that a maximum or a minimum is present in the
central track section. Then the adjustment screws are adjusted at the point of the extreme misalignment and the surrounding vicinity according to the determined misalignment. As mentioned above, this should be carried out in
small steps. Finally, the straightness of the track should be
tested along the whole track. If the misalignment exhibits a
number of extreme points, then an analogous procedure
should be followed for their correction.
4 EXPERIMENT LITERATURE
Versuchseinheiten Physik,
Lineare Bewegungen 16001.01
Physik in Demonstrationsversuchen,
Ausgabe A/B, Band Mechanik 01141.21
Physik in Demonstrationsversuchen,
Ausgabe C, Teil 1 01146.01
University Practicals in Physics 00067.72
Manual for COMEX Air Track Rail 01171.02
Computer-Aided Measurement Acquisition and Evaluation
of Air Track Rail Experiments with the COMEX Interface System
3
11202.17
5 LIST OF EQUIPMENT
5.1 Items supplied in 11202.77
1 Air Track Rail 11202.17
2 End-Holder (23) 11202.15
3 Glider (23) 11202.02
4 Screen, l = 100mm (23) 11202.03
4 Screen, l = 25mm (23) 11202.04
5 Fork with Plug 11202.08
6 Rubber Band, 10 pcs. 11202.09
7 Plate with Plug 11202.10
8 Tube with Plug 11202.05
9 Needle with Plug 11202.06
5.2 Other parts required
(not included in 11202.77)
10 Blower 13770.93
11 Pressure Tube, l = 1.5m with
end connections 11205.01
12 Precision Pulley 11201.02
13 Weight Holder 02407.00
14 lotted Weight 1g, natural colour (53) 03916.00
15 Slotted Weight 50g, black (83) 02206.01
16 Silk Thread, l = 200m 02412.00
17 Hook with Plug 11202.07
18 Starting System, mechanical, with trigger 11202.13
19 Magnet with Plug 11202.14
20 Jet Glider 11202.23
21 Stop, adjustable (as alternative
to End-Holder 2)(23) 11202.19
22 Air Damping 11202.20
As alternative
to the mechanical starting system 18, 19:
Starting system, electromagnetic,
consisting of:
23 Coil 400 turns 07829.01
24 Iron Core 11202.16
25 Holder with Plug 11202.11
5 Fork with Plug 11202.08
6 Rubber Band, 1 pc. from 11202.09
26 Silicon Diode 1N4007 39106.02
with no illustration:
Light Barrier (23) 11207.02
Electronic Digital Counter
4 Decade 13600.93
6 Decade 13603.93
(Both counters supply the 5V voltage required for
operating the light barriers.)
Plasticine 03935.03
Wall Bracket for Air Track Rail 11202.25
Dust Cover for Air Track Rail 11202.21
4
11202.17
The COMEX System with the Tracking Plug-in Unit
(12005.00), the Light-Barrier Rail (12005.01) and the Air
Track Rail Program (1412.51) gives the possibility of conducting, evaluating and impressively demonstrating numerous new experiments with the air track rail and also experiments that have already been well proven in education.
The positions and velocities of the gliders are measured
with a time resolution of 5 millionths of a second and passed to the computer. Already after only one run up to 80
items of data about time, position and velocity are available
which can be displayed numerically or graphically. Through
simultaneous tracking of two, completely independent gliders in any direction of movement, the laws of collision and
the conservation of momentum can be experimentally investigated in an easy and methodically clear manner. The
measurements can be immediately checked with respect to
their physical relationships in special display windows in the
program.
Technical data
Memory capacity
up to 5 screen passes per single light barrier with ab-
solute time and shading duration.
Time resolution
1/187.5kHz for shading duration
1/5.558kHz for absolute time
Duration of experiment
maximum 11s
Connection of light-barrier rail
via 14-pole socket
IEC device address 6
Housing
plug-in cassette 19, 3 ht. divs.
Material
COMEX Basic Unit 12000.93
for housing and supply of COMEX plug-in units.
IEEE-488 Bus Interface 12000.20
for IBM-PC and compatible computers
IEEE-488 Connecting Cable 17579.10
COMEX Tracking Plug-in Unit 12005.00
Light-Barrier Rail 12005.01
for measuring the motion sequences on the air track rail; 8
light barriers at intervals of 200mm; 14-pole socket for
connection of the tracking plug-in unit; 2 adjustable support
bars for holding the rail in various positions; dimensions:
160 3 8 3 4 (cm).
The following are contained in 12005.01:
Connecting lead for the light-barrier rail.
Precision Screens, Set of 12005.02
cf. Item 27, page 2
Program for tracking plug-in unit:
Diskette, Air Track Rail 14142.51
for measurement acquisition and evaluation of experiments
with 1 or 2 gliders, e.g. elastic/inelastic collisions, laws of
conservation of energy/momentum, tabular and graphical
evaluation...
The program runs on all IBM-PC and compatible computers
and automatically supports CGA, EGA, VGA and HGC graphics cards. All graphs and tables can be output with comments via Epson compatible matrix printers. With collision
experiments the measurement points are displayed with different symbols (before and after the collision) and when
using two gliders the motion curves are displayed in different colours. Therefore, it can be easily seen which glider
has produced each point and which direction it was moving
at that point in time.
5
11202.17
Computer-Aided Measurement
Acquisition and Evaluation of Air Track Rail
Experiments with the COMEX System
The air track rail used with the COMEX System including the tracking plug-in unit and the light barrier rail.
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