PASCO ME-6992B User manual

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PASCO Structures System
Advanced Structures Set
ME-6992B
Instruction Manual
012-12719B
*012-12719*

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The PASCO Advanced Structures Set includes the ME-6988A Force Structures Bracket for connecting a struc-
ture to a PASCO Force Platform.

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Table of Contents
Included Items . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Related and Recommended Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
About the Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Adding Load Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Properties of I-Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Simple Triangles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Trusses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Common Truss Bridges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Different Scales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Measuring Bridge Deflection Under Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Bridge Challenges for Students . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Measuring Static and Dynamic Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Forces on a Boom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Human Leg Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Teeter Totter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Human Back Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Tower Crane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Human Arm Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Angle Crane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Catapult . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Camelback Truss Bridge and Multilength Combinations . . . . . . . . . . . . . . . . . . . . . . . . 27
Truss Bridge with Cross Bracing and Trestle with Cross Bracing . . . . . . . . . . . . . . . . . 28
PAStrack Trestle with Cross Bracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Tower with Cross Bracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Rubber Band Powered “Car” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

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Advanced Structures Set
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Spares Part Numbers and Summary of Extra Equipment . . . . . . . . . . . . . . . . . . . . . . . 32
Bridges That Require an Advanced Set and a Bridge Set. . . . . . . . . . . . . . . . . . . . . . . 33
I-Beam Suspension Bridge Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
I-Beam Suspension Bridge End Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
I-Beam Suspension Bridge Tower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
I-Beam Suspension Bridge Road Bed Assembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Flexible I-Beam Suspension Bridge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Flat Beam Suspension Bridge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Cable Stayed Bridge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Cable Stayed Bridge Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Baltimore Bridge and Arched Causeway Bridge Details 1. . . . . . . . . . . . . . . . . . . . . . . 41
Arch Truss Bridge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Cantilevered Truss Bridge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Tied Arch Bridge with Cross Bracing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Double Tied Arch Bridge with Flexible I-Beams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
PAStrack Cable Stayed Bridge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Cable Stayed Bridge Construction Suggestions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Resonance Structures: Beam and Tower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Force Platform Structures Bracket. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Technical Support, Warranty, and Copyright. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Advanced Structures Set
ME-6992B
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Included Items Qty Included Items Qty
1. #5 Beam (24 cm long) 24 16. Drive Wheel and Tire 4
2. #4 Beam (17 cm long) 54 17. Straight Connector 24
3. #3 Beam (11.5 cm long) 54 18. Structures Rod Clamp 2
4. #2 Beam (8 cm long) 24 19. Nut and Bolt for PAStrack 6
5. #1 Beam (5.5 cm long) 24 20. Screw (6-32) 300
6. #3 Flexible Beam (11.5 cm) 16 21. “O” Ring 12
7. #4 Flexible Beam (17 cm) 16 22. Pulley 12
8. #5 Flexible Beam (24 cm) 16 23. Collet 24
9. Flat 3 X 4 Beam (19 cm) 16 24. Spacer 12
10. Flat #4 Beam (17 cm) 16 25. Sliding Connector 12
11. Flat 2 X 3 Beam (12.5 cm) 16 26. Angle Connector 24
12. Flat Connector 6 27. Cord Tensioning Clip 32
13. Full Round Connector 6 28. Yellow Cord 1 roll
14. Half Round Connector 42 Force Structures Bracket (not shown) 2
15. Axle (2 each of 3 lengths) 6 Storage Box (not shown) 1
16
17
19
14
8
5
12
9
15
13 11
10
3
7
6
4
2
1
15
15
18
20 21
22
23
24
26
25
27
28

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Advanced Structures Set Introduction
2012-12719B
The ME-6992B Advanced Structures Set consists of items from the following components of the PASCO Struc-
tures System.
Other PASCO equipment is closely related to the Advanced Structures Set..
*See the PASCO catalog or PASCO web site (www.pasco.com) for more information
Introduction
The ME-6992B Advanced Structures Set is one part of the PASCO Structures System. The Advanced Structures
Set can be used as a stand-alone set and it can also be combined with other parts of the PASCO Structures Sys-
tem. The Load Cell and Amplifier Set (PS-2199) can be added to measure compression and tension forces in the
structure members and other sets of plastic parts are available.
Other parts of the PASCO Structures System include the following:
Physics Structures Set (ME-6989) - A set of structure items (e.g., beams, connectors, screws) and other equip-
ment designed for studying kinematics, momentum, energy, and rotation.
Truss Set (ME-6990) - A small set of beams, connectors, and screws for building trusses.
Bridge Set (ME-6991) - A larger set with road bed and cables for building bridges and roller coasters.
Load Cell Amplifier (PS-2198) - Can plug in up to six Load Cells; requires a PASPORT interface to connect to
the USB port of a computer.
Load Cell and Amplifier Set (PS-2199) - Load Cell Amplifier (PS-2198) with four 100 N Load Cells
(PS-2200).
ME-6985 Flexible I-Beam Set ME-6996 Cord Lock Spares
ME-6986 Structures Rod Clamp (2) ME-6997 Full Round Connectors
ME-6987 Flat Structures Members ME-6998A Axle Spares
ME-6993 Truss Set Members ME-6999A Angle Connectors
ME-6994 Truss Set Screws 740-162 Storage Box (12 quart)
Related Equipment Related Equipment
PS-2198 Load Cell Amplifier ME-6989 Physics Structures Set
PS-2199 Load Cell and Amplifier Set ME-6990 Truss Set
PS-2200 100-N Load Cell ME-6991 Bridge Set
PS-2201 5-N Load Cell ME-6995 Road Bed Spares
PS-2205 Displacement Sensor PASPORT Interfaces*
PS-2206 Dual Load Cell Amplifier Data Acquisition Software*
Recommended Equipment Recommended Equipment
Hooked Mass Set (SE-8759) Large Slotted Mass Sets (ME-7566 and ME-7589)
Mass and Hanger set (ME-8979) Angle Indicator (ME-9495A)
PASPORT Force Platform (PS-2141) 2-Axis Force Platform (PS-2142)

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Model No. ME-6992B About the Components
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012-12719B
100 N Load Cell (PS-2200) - Strain gauges mounted on a beam with no electronics so a Load Cell requires a
Load Cell Amplifier (PS-2198) or Dual Load Cell Amplifier PS-2206).
5 N Load Cell (PS-2201) - Strain gauges mounted on a beam with no electronics so a Load Cell requires a Load
Cell Amplifier or Dual Load Cell Amplifier.
Displacement Sensor (PS-2205) - A PASPORT Sensor and a digital displacement indicator designed to measure
the deflection of parts of a structure such as a truss or a bridge.
Dual Load Cell Amplifier (PS-2206) - Can plug in one or two Load Cells; requires a PASPORT interface to
connect to the USB port of a computer.
About the Components
Beams
There are five sizes of plastic I-Beams, labeled #1 through #5. Beam #1 is the shortest beam. There are three
sizes of Flexible I-Beams labeled #3, #4, and #5, and three sizes of Flat Beams labeled 2 X 3, F4, and 3 X 4.
Assembling Beams
All beams attach to connectors in the same way. Use the included screws (6-32, slotted) to attach beams to a con-
nector (such as the half round connector) as illustrated.
Flexible I-Beams
Flexible I-Beams are the same size as the #3, #4, and #5 I-Beams, but they can be used to dramatically demon-
strate structure failure under a heavy load. The beams will return to their original shape when the load is
removed.
Figure 1: Attaching beams to connectors
Figure 2: Flexible
I-Beams
Flexible I-Beams are also
used in the construction of
suspension bridge models.

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Advanced Structures Set About the Components
4012-12719B
Flat Beams
Flat Beams are used for cross-bracing.
Attaching Cords
When attaching cords for lateral bracing or for suspension or cable-stayed
bridges, Cord Tensioning Clips are used to assist in adjusting the tension in
the cords.
The Cord Clip does not come apart. It is best to thread the cord through the
clip before the clip is installed on the bridge or structure. Prepare to thread
the cord by holding the top half of the clip as shown in Figure 4a so the two halves of the clip will separate, leav-
ing an opening through which the cord is threaded. The cord is inserted into the end opposite the pointed end of
the clip. The cord should be looped back through the clip as shown in Figure 4c. Then the Cord Clip can be used
in the structure, using the attachment screw to tighten the clip shut. To adjust the cord tension, loosen the screw
and pull on the cord to the desired tension and then tighten the screw.
Connectors
Half Round Connector: The half round connector has eight slots,
labeled A through H, for accepting beams.
Full Round Connector: The full round connector has eleven slots,
labeled A through H and X, Y, and Z, for attaching beams
Flat Connector: The flat connector has eight slots, labeled A through
E, and X, Y, and Z, for attaching beams.
Straight Connector: The straight connector can connect two beams to
make a longer beam.
Angle Connector: The angle connector can allow a beam to be con-
nected to a half round connector, full round connector, or flat connec-
tor at an angle different than zero, 45, or 90 degrees. The Angle
Connector also allows for a small adjustment of the length of the
beam.
Sliding Connector: The sliding connector allows one beam to be con-
nected to another beam at any position along the length of the second
beam. To use the sliding connector, loosen the thumbscrew and rotate
the top “jaw” to the side. Place the beam onto the lower part of the
connector, rotate the top “jaw” into place, and tighten the thumbscrew.
2 X 3 Flat Beams
Figure 3: Flat Beams
#3
#2
Figure 4a: Hold half of
the cord clip so the
two halves separate
Figure 4b: Loop the
cord back through the
cord clip
Figure 4c: The cord
goes around the
screw hole
Figure 4d: The cord clip is
ready to be attached to the
structure using a screw
Half Round
Full Round Flat
Straight Angle
Figure 5: Connectors
Sliding
I-Beam #1
“Jaw”
Top view

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Model No. ME-6992B Adding Load Cells
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012-12719B
Nut and Bolt for PAStrack: The square nut and bolt can be used with a flat connector to
fasten a bridge or other structure to the PASCO PAStrack (see the PASCO catalog or
web site at www.pasco.com for information about PAStrack equipment.)
Axles, Pulleys, Spacers, Collets, and Drive Wheels
Axles: There are two each of three different lengths: 10.4 cm (4.1 in), 21.3
cm (8.4 in), and 26.6 cm (10.5 in). Each axle is 0.635 cm (0.250 in) in
diameter.
Pulleys: There are twelve pulleys, each 3.175 cm (1.250 in) in diameter
and 0.558 cm (0.220 in) wide. To make a wheel, put one of the “O” rings
into the pulley’s groove.
Spacers: There are twelve spacers, each 0.635 cm (0.250 in) inside diame-
ter, 1.25 cm (0.50 in) outside diameter, and 0.635 cm (0.250 in) wide.Col-
lets: There are twenty-four collets that can be used with screws (6-32) to
hold pulleys and spacers in place on an axle.
Drive Wheel with Tire: There are four drive wheels with tires. The drive
wheel can be attached to an axle using a thumbscrew. To attach the wheel firmly to the axle, line up a hole on the
axle with the thumbscrew hole on the wheel. If the rubber tire is removed, the wheel can be used as a large pul-
ley.
Force Platform Structure (ME-6988A)
The PASCO model ME-6988A Force Platform Structures Bracket includes two brackets and four thumbscrews.
The adapter bracket is designed to connect members of the PASCO Structures System to a PASCO Force Platform
(not included). The brackets can also serve as foundation plates for larger structure models.
(Please see the Force Platform Structures Bracket instruction sheet for more information.)
Adding Load Cells
To measure the compression and tension forces in
individual members, add load cells (e.g., PASCO
Model PS-2200) to any PASCO Structure. Replace a
beam with two shorter beams and a load cell.
#5 beam = load cell + two #3 beams
#4 beam = load cell + two #2 beams
#3 beam = load cell + two #1 beams
Use thumbscrews to attach two beams to a load cell as
shown in Figure 8.
When using load cells, assemble your structure with the screws loose. This will simplify the analysis by ensuring
that the members experience only tension and compression without moments.
See the instructions that came with the load cells for details about how to connect the load cells to an interface or
datalogger and collect data.
Figure 6: Nut and
Bolt for PAStrack
Figure 7: Axle items
Axle
O-Ring
PulleySpacer
Collet
Drive
Wheel
Figure 8: A load cell combined with two #2 beams is
the same length as a #4 beam

®
Advanced Structures Set Properties of I-beams
6012-12719B
Example: Bridge with Load Cells
The bridge shown in Figure 9 incorporates six load
cells to measure the tension or compression in vari-
ous members. A hanging mass is used to apply load.
The mass is adjusted so that the compression in one
of the legs is 1.0 N. Compression is registered as a
positive value and tension as a negative value.
If the screws are loose, the theoretical analysis of
the bridge can be carried out by assuming that the
net force at each node is zero. Thus, the vertical
component of compression in the left-most diagonal member must be 1 N (to oppose the force applied by the
leg). The horizontal component must also be 1 N since the member is at a 45° angle. The predicted resultant
force is:
The actual measured force confirms the theory.
Calibration of Load Cells
Load cells are factory calibrated; however, you can re-calibrate them in
software or on the datalogger. Assemble the fixture shown in Figure 10
to support the load cell. See the documentation for your software or
datalogger for instructions.
When calibrating a load cell, it is necessary to apply a known load. Hold
or clamp the fixture at the edge of a table and hang a mass from it as
shown.
Note that the hanging mass applies tension to the load cell; therefore the
known force that you enter into the software or datalogger should be a
negative value. For example, if the mass is 1.0 kg, the applied force is
-9.8 N.
Properties of I-beams
Figure 11 shows the difference between the X
and Y bending moments of an I-beam.
Simple Triangles
Most structures are made of isosceles right tri-
angles as shown in Figure 12.
Figure 9: Bridge with Load Cells
1.0 N
21.0 N 2
+ 1.4 N=
Figure 10:
Calibration fixture
Load Cell
Mass
Figure 11: Bending an I-Beam
#4
#4
#5 #4
#3
#3
#3
#2
#2
#2
#1
#1
Figure 12: (Left) A triangle made from a #5 beam and two #4 beams. (Right) Combinations of beams to make triangles.
Half Round
connector

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Model No. ME-6992B Trusses
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012-12719B
Trusses
Kingpost Truss
Figure 13 shows a simple king-
post truss made from #5 and #4
beams. Use a hanging mass to
apply a load.
Lay the kingpost truss on the
table to compare its horizontal
and vertical stiffness.
To build a three-dimensional
structure, connect two trusses with #4
beams (Figure 14).
Add cross bracing to increase stiffness.
Queenpost Truss
To make a queenpost truss, separate the
kingpost truss in the middle and add a
square section..
Legs can be added to any truss or bridge (Figure 15).
Roof Truss
Use #4 and #5 beams to build a simple roof truss or a roof truss structure with legs.
Figure 13: A simple
kingpost truss
#4
#4
#4
#5 #5
Figure 14: (Left) A three-dimensional kingpost truss structure.
(Right) Kingpost truss with cross bracing.
#5 #5
#4
#4
#4
#4
#4#4
Figure 15: (Left) Diagram of queenpost truss (Middle) Queenpost truss (Right) Queenpost truss with legs
#4 #4 #4
#4
#4 #4
#5
#5
#5
Figure 16: Roof truss

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Advanced Structures Set Common Truss Bridges
8012-12719B
Common Truss Bridges
Warren Bridge
The Warren Bridge (Figure 17) is a simple type of bridge consisting of a series of triangles. However, a simple
Warren Bridge is not practical for supporting a deck (road bed). Vertical members can be added to support the
deck. Additional verticals can support an upper deck.
To make a free-standing bridge, begin by laying out one side of the bridge on a table. Then build the other side of
the bridge. Join the two sides of the bridge attaching the floor beams and the top cross beams. Use additional
members as piers to support the bridge. (Figure 18).
Different Scales
It is possible to build bridges of two different
scales. Figure 19 shows a Warren with Verticals
built to two different scales.
In spanning a particular distance, why wouldn’t
you use the smaller scale bridge and add more
panels? An examination of the forces in the mem-
bers of each size bridge will give the answer. If
the smaller and larger bridges have the same num-
ber of panels and experience the same load, the
forces in any member of the smaller bridge is the
same as the same member in the larger bridge.
Each additional panel is submitted to larger
forces. This can be explored using load cells. See
the section on Measurement of Static and
Dynamic Loads
Figures 20 and 21 show different bridges. Investi-
gate how the forces in these bridges differ from
the Warren.
Figure 18: Free-standing
Warren bridge
Figure 17: (Top) Warren bridge (Middle) Warren
with deck verticals (Bottom) Warren with verticals
#4
#5
#3
#3
#3
#4
#3
#3
#4
#5
Figure 20: (Top) Pratt. (Bottom) Howe
Figure 19: Smaller and larger scale Warren with verticals
#3
#4
#5
#3
Figure 21: Free-standing Howe

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Model No. ME-6992B Measuring Bridge Deflection Under Load
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012-12719B
Measuring Bridge Deflection Under Load
Because the members are made of plastic, it is easy to show bending in a bridge
using relatively small loads.
Using a Motion Sensor
In Figure 22, the bridge is loaded by hanging a weight (Large Slotted Mass Set, PASCO Model ME-7566) from
the center of the bridge. A Motion Sensor (PS-2103) is placed on the floor and pointed up toward the bottom of
the weight hanger. A PASPORT interface (in this case, the Xplorer GLX, PS-2002) is used to record the amount
of mass and the distance to the bottom of the weight hanger. A graph of the deflection as a function of the load is
shown next to Figure 22.
Hint: For the GLX, set the Motion Sensor sample rate to 50 Hz. In the Sensor Setup window, change the
‘Reduce/Smooth Averaging’ from ‘Off’ to ‘5 points’.
Using Load Cells
Figure 23 shows two bridges of the same type but different scale. For a given load the deflection is different.
Also note that the forces in some of the members are being measured using load cells to discover the difference
caused by the size of the bridge.
Bridge Challenges for Students
Perhaps the best way for students to learn about bridges is to give them a task to accomplish with limited
resources by any means possible. Here are two suggestions to challenge your students.
NOTE: Do not attempt to
load the bridge to the
point of breaking.
Figure 22: (Left) Deflection of bridge under load.
(Above) Displacement vs. Mass plotted using
PASCO’s DataStudio software.
Figure 23: (Above) Same load for different scale bridges. (Right) Displacement vs. Mass

®
Advanced Structures Set Measuring Static and Dynamic Loading
10 012-12719B
Span a Gap
Give each group a set of plastic, half of a Bridge Set or a Truss Set. The goal is to span a gap of 60 cm. Then find
the member with the greatest compression and change the design of the bridge to minimize the maximum com-
pression.
Least Deflection Under Load
Give each group a Bridge Set. The goal is to span a given distance with a bridge that has the least deflection
under load. The bridge is loaded with a particular load that the bridge must be able to bear. The bridge that has
the least defection is the winner.
Measuring Static and Dynamic Loading
Static Load
Apply a static load to the bridge by hanging a
hooked mass from one of the floor beams and
insert load cells into the structure as shown in
Figure 24. Loosen all the screws in the structure
so the members are resting on their pins. This will
eliminate any extra moments due to the screws
and the tension and compression readings will
agree with the calculated values.
Dynamic Load
With the load cells inserted as shown in Figure
25, push the Dynamics Cart with its extra mass across the bridge. Zero the load cells before the measurement.
Examine which members are under tension or compression.
Figure 24: Measuring a static load
Figure 25: (Above) Recording the forces measured by the load cells as the cart traverses the PAStrack bridge.
(Right) DataStudio plot of load cell data.
PAStrack
Load
cell Load cell
amplifier
Adjustable
end stop

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Model No. ME-6992B Forces on a Boom
Forces on a Boom
Full
Round
Angle
Connector
Hooked
Mass
Slotted
Masses
Straight
Connector
Half Round
Angle
Connector
Axle
(Medium)
Screw
Half
Round
Half
Round
#2
#3
#4
#4
#3
#5
#5
Load
Cell
#3
#1
#1
Boom Detail
Load Cell Detail
Cord
Cord
Cord
Attach a cord from the Load Cell
over the pulley to the boom.
Flat
Connector
#2 Stackslotted masseson
the flat connector.
Straight
Connector
Half
Round
#1
Pulley
Axle
(Short)
Angle
Connector
Half
Round
Cord
Tensioning
Clip
Full
Round
#1
Load Cell
Angle
Connector
#3
#1
#1
Top Pulley Detail
Half
Round
Angle
Connector
Full
Round #3
#3
#3
Half
Round
#1
#1
Extra Equipment Model Extra Equipment Model
Hooked Mass Set SE-8759 Angle Indicator ME-9495
Large Slotted Mass Set ME-7566 Load Cell & Amplifier Set PS-2199

®
Advanced Structures Set Forces on a Boom
12 012-12719B
Forces on a Boom: Details
Load Cells
The “Forces on a Boom” structure is shown with four Load Cells measuring the horizontal and vertical forces of
the axle on the base of the boom. The experiment can be performed using only two Load Cells on the base, both
on one side, but care must be given to ensure that the boom is centered and balanced side-to-side. The actual
force will be two times the measured value.
Suggestions
The triangular support structure for the upper pulley is constructed to allow the cord to be horizontal. By using
different components, students can change the height of the pulley and thus vary the angle of the cord. How does
that affect the measured forces?
The supporting cord is shown tied to a cross member near the end of the boom. What changes if the cord is
moved to the end of the boom or to a cross member closer to the base of the boom?
Angle Indicator
The ME-9495 Angle Indicator can be used both on the cord and on the boom itself.
Force Vector Diagram
The following diagram shows the various forces acting on the boom.
W
Wb
T

Fy
Fx

®
13
Model No. ME-6992B Human Leg Model
Human Leg Model
Load Cell
Full
Round
#2
#3
Half
Round
Half
Round #1
#1
Half
Round
Pulley
Collet
Axle
(Medium)
#1
Spacer
Axle
(Medium)
Half
Round
Screw
Angle
Connector
Angle
Connector
Straight
Connector
#4
#5
#3
#3
Half
Round
#1
Half
Round
Angle
Connector
#3
#5
#5
#3
#1
Flat
Connector
#2
Attach cord to
this I-beam
Cord
Cord
Angle
Connector
#2
Load Cell Detail
“Knee” Detail
Stack masses on
the flat connector.
Use a cord tensioning clip to connect a cord to the Load Cell. Put the cord over the
pulley and attach the end to the front cross-member of the “knee”.
Extra Equipment Model
Large Slotted Mass Set ME-7566
Large Table Clamp ME-9472
Load Cell & Amplifier Set PS-2199
Angle
Connector
#1
Screw

®
Advanced Structures Set Human Leg Model
14 012-12719B
Human Leg Model: Details
Knee Forces
Directly measure the force needed to support the leg at various angles.
Leg Model
The articulated leg uses a rubber band (not included) as the quadriceps muscle and has a Load Cell on the foot to
measure the force that the “toe” exerts on the ball. The impulse (area under the curve of force versus time) is
equal to the resulting momentum of the ball.
The Load Cell represents
the quadricep muscle in
the upper leg.
W

Large Table Clamp
Load
Cell
Load Cell Amplifier

®
15
Model No. ME-6992B Teeter Totter
Teeter Totter
Half
Round Half
Round
Axle
(Medium)
#1
#2
#4
#5
#4
Straight
Connector
#4
#4
#4
#4
#4
#4
#2
#1
Angle
Connector
Half
Round
Axle
(Medium)
#2
#2
#4
#4
Use a hanger and mass at this
end and a hooked mass at the
other end.
Pivot Detail
Short End of Teeter Totter Detail
Extra Equipment Model
Hooked Mass Set SE-8759
Mass and Hanger Set ME-8979

®
Advanced Structures Set TeeterTotter
16 012-12719B
Teeter Totter: Details
Suggestions
Vary the length of the teeter totter by increasing or decreasing the number of segments or sections.
Vary the placement of the pivot: it does not have to be as shown.
Place the hanging masses at different locations.
How will you know that the torque on the right side equals the torque on the left side?
Mass and
Hanger Hooked
Mass