PASCO ME-6992B User Manual

Instruction Manual

012-12719B

*012-12719*

PASCO Structures System

Advanced Structures Set

ME-6992B

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

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

iii

Advanced Structures Set

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

15 15

ME-6992B

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 (n ot shown) 2

15. Axle (2 each of 3 lengths) 6 Storage Box (not shown) 1

Advanced Structures Set Introduction

The ME-6992B Advanced Structures Set consists of items from the following components of the PASCO Structures System.

ME-6985 Flexible I-Beam Set ME-6996 Cord Lock Spares ME-6986 Structur es 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)

Other PASCO equipment is closely related to the Advanced Structures Set..

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*

*See the PASCO catalog or PASCO web site (www.pasco.com) for more information

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)

Introduction

The ME-6992B Advanced Structures Set is one part of the P ASCO S tructures System . The Advanced S tructures Set can be used as a stand-alone set and it can also be combined with other parts of the PASCO Structures System. 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, connect ors, screws) and other equipment 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).

012-12719B

Model No. ME-6992B About the Components

Figure 1: Attaching beams to connectors

Figure 2: Flexible

I-Beams

Flexible I-Beams are also used in the construction of suspension bridge models.

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 P ASPORT 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. Us e the included screws (6-32, slotted) to attach beams to a connector (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 demonstrate structure failure under a heavy load. The beams will return to their original shape when the load is removed.

012-12719B

Advanced Structures Set About the Components

2 X 3 Flat Beams

Figure 3: Flat Beams

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”

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 T ensioning 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, leaving 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 connected to a half round connector, full round connector, or flat connector 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 connected to another beam at any position along the length of the second beam. T o 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.

Top view

012-12719B

Model No. ME-6992B Adding Load Cells

Figure 6: Nut and Bolt for PAStrack

Figure 7: Axle items

Axle

O-Ring

Pulley

Spacer

Collet

Drive

Wheel

Figure 8: A load cell combined with two #2 beams is

the same length as a #4 beam

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 diameter, 1.25 cm (0.50 in) outside diameter, and 0.635 cm (0.250 in) wide.Collets: 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 pulley.

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.

012-12719B

Advanced Structures Set Properties of I-beams

Figure 9: Bridge with Load Cells

1.0 N21.0 N

+ 1.4 N=

Figure 10:

Calibration fixture

Load Cell

Mass

Figure 11: Bending an I-Beam

Figure 12: (Left) A triangle made from a #5 beam and two #4 beams. (Right) Combinations of beams to make triangles.

Half Round

connector

Example: Bridge with Load Cells

The bridge shown in Figure 9 incorporates six load cells to measure the tension or compression in various 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 oppo se 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 triangles as shown in Figure 12.

012-12719B

Model No. ME-6992B Trusses

Figure 13: A simple

kingpost truss

Figure 14: (Left) A three-dimensional kingpost truss structure.

(Right) Kingpost truss with cross bracing.

#5 #5

#4#4

Figure 15: (Left) Diagram of queenpost truss (Middle) Queenpost tru ss (Right) Queenpost truss with legs

Figure 16: Roof truss

Trusses

Kingpost Truss

Figure 13 shows a simple kingpost 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.

012-12719B

Advanced Structures Set Common Truss Bridges

Figure 18: Free-standing

Warren bridge

Figure 17: (Top) Warren bridge (Middle) Warren

Figure 20: (Top) Pratt. (Bottom) Howe

Figure 19: Smaller and larger scale Warren with verticals

Figure 21: Free-standing Howe

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 Brid ge 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.

T o 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 members of each size bridge will give the answer. If the smaller and larger bridges have the same number 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. Investigate how the forces in these bridges differ from the Warren.

012-12719B

Model No. ME-6 992B Measuring Bridge Deflection Under Load

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

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.

012-12719B

Advanced Structures Set Measuring Static and Dynamic Loading

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

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 compression.

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.

012-12719B

Full

Round

Angle

Connector

Hooked

Mass

Slotted

Masses

Straight

Connector

Half Round

Angle

Connector

Axle

(Medium)

Screw

Half

Round

Half

Round

Load

Cell

Boom Detail

Load Cell Detail

Cord

Attach a cord from the Load Cell over the pulley to the boom.

Flat

Connector

Stack slotted masses on

the flat connector.

Straight

Connector

Half

Round

Pulley

Axle

(Short)

Angle

Connector

Half

Round

Cord

Tensioning

Clip

Full

Round

Load Cell

Angle

Connector

Top Pulley Detail

Half

Round

Angle

Connector

Full

Round

Half

Round

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

Model No. ME-6992B Forces on a Boom

Forces on a Boom

Advanced Structures Set Forces on a Boom



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.

012-12719B

Model No. ME-6992B Human Leg Model

Load Cell

Full

Round

Half

Round

Half

Round

Half

Round

Pulley

Collet

Axle

(Medium)

Spacer

Axle

(Medium)

Half

Round

Screw

Angle

Connector

Angle

Connector

Straight

Connector

Half

Round

Half

Round

Angle

Connector

Flat

Connector

Attach cord to

this I-beam

Cord

Angle

Connector

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

Human Leg Model

Connector

Angle

Screw

Advanced Structures Set Human Leg Model

The Load Cell represents

the quadricep muscle in

the upper leg.



Large Table Clamp

Load

Cell

Load Cell Amplifier

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.

012-12719B

+ 40 hidden pages

PASCO ME-6992B User Manual

Table of Contents

Introduction

About the Components

Beams

Assembling Beams

Flexible I-Beams

Flat Beams

Attaching Cords

Connectors

Axles, Pulleys, Spacers, Collets, and Drive Wheels

Force Platform Structure (ME-6988A)

Adding Load Cells

Example: Bridge with Load Cells

Calibration of Load Cells

Properties of I-beams

Simple Triangles

kingpost truss

Trusses

Queenpost Truss

Roof Truss

Warren bridge

Common Truss Bridges

Different Scales

Measuring Bridge Deflection Under Load

Using a Motion Sensor

Using Load Cells

Bridge Challenges for Students

Span a Gap

Least Deflection Under Load

Measuring Static and Dynamic Loading

Static Load

Dynamic Load

Forces on a Boom

Forces on a Boom: Details

Human Leg Model

Human Leg Model: Details