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Force Platform
CI-6461
Instruction Manual
012-09493A
Included Equipment Part Number
Force Platform CI-6461
Required Equipment
ScienceWorkshop
Optional Equipment
Handle Set PS-2548
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Compatible ScienceWorkshop interfaces include the ScienceWorkshop 750 (CI-7650),
ScienceWorkshop 500 (CI-6400), and others. See the PASCO catalog, visit www.pasco.com, or contact
PASCO tech support for more information.
Interface
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See PASCO catalog or www.pasco.com
Introduction
The ScienceWorkshop Force Platform, used with a ScienceWorkshop interface, continuously measures force (up
to 4400 N or 1000 pounds) applied by a person or object. You can use the Force Platform to measure the static
weight of a person standing on it, or the dynamic vertical force involved in moving and jumping. It has the measurement range and strength to accommodate people of all sizes and the sensitivity to measure smaller forces
such as the weight of a ball. Put the platform on the floor or tabletop to measure vertical force, or mount it on a
wall to measure horizontal force. With the optional handle set, you can use the platform to measure both “pulling” and “pushing” force.
800-772-8700 www.pasco.com
Force Platform How It Works
How It Works
When an object is placed on the Force Platform, it applies a force normal to the platform's surface; this force is the object's weight. Because the Force Platform does not
move (much), the force applied by the floor to the platform's feet increases by an
amount equal to the object’s weight. Each of the four feet is connected to a beam with
a strain gauge, through which the platform's electronics measure the force. The platform outputs a voltage proportional to the sum of these four forces, which is read by
the interface and translated into a force measurement (in newtons or pounds) by
DataStudio software. Force is measured in this way even if it is not constant, for
instance, the force applied by a bouncing ball or jumping person.
Hardware Setup
On the floor
Place the Force Platform on the floor. It works best on a hard
floor such as tile or wood, rather than carpet, which would
allow the platform to move slightly when you step on it. If the
floor is not perfectly level, adjust the platform's feet by turning
them to make the platform level and stable. The platform
should have all four feet on the floor with nothing touching
the flat bottom surface.
Hang the Force Platform using side tabs
Turn feet to level Force Platform
On a Wall
To measure horizontal force, use the tabs on the side of the
platform to hang it from a pair of bolts or hooks on a wall.
Make sure that all four feet are in stable contact with the wall.
With the Optional Handle Set
Fasten the handles to the threaded brass inserts on the top of
the platform, or remove the feet and fasten the handles to the
bottom of the platform. With the handles, you can hold the
platform against a wall to measure horizontal pushing force. If
you have two platforms with handles (attached to the bottom),
you can demonstrate Newton's third law by pushing the platforms together. Note that the platform measures only the component of force normal to the surface.
Optional handles
attached to bottom of
Force Platform
Interface and Software Setup
Connect the platform's cable to channel A, B, or C of a ScienceWorkshop interface. A
green LED on the side of the platform lights to indicate that the unit is powered and
ready to take data. Press the tare button to set the output to zero.
Tare button
Using the Force Platform with DataStudio
Start DataStudio. In the Experiment Setup window, click the channel that the Force
Platform is connected to and select Force Platform from the sensors list. Click the
Start button to begin data collection. By default, the platform collects data at 10 samples per second and displays it in units of newtons (N). You can change these settings
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Model No. CI-6461 Safety
in the Experiment Setup window. (Click the Setup button to open the window.) For
more instructions on using DataStudio, press F1 to open DataStudio's on-line help.
For Best-possible Resolution
The ScienceWorkshop 750 Interface uses 8x oversampling to improve resolution at
lower sampling rates. To take advantage of oversampling, set the sampling rate to 100
Hz or less.
For measuring a static or slowly changing force, set the sampling rate to 100
Hz and create this calculation (or similar) in the DataStudio calculator:
Force = avgfilter(10, F)
Define the variable F as the force measurement from the sensor. In this
example, the calculation reduces the number of data points and improves the
resolution by a factor of 10 (as determined by the first argument of the
avgfilter function).
Sampling Rate and Impulse Measurement
The model CI-6461 Force Platform updates its analog output once every 6 ms, therefor the fastest practical sampling rate is about 200 Hz. This rate is fast enough to
accurately measure longer-duration impulses such as that of a person jumping. To
measure the impulse of a bouncing ball, the impulse should last at least 30 ms. Use a
soft or under-inflated ball that will stay in contact with the platform for as long as possible with each bounce.
Safety
Teachers: The Force Platform is designed for use by students under the supervision of a
teacher. Ensure that all users understand and follow these guidelines when jumping or stepping on the platform.
• Do not stand on or jump off tables, chairs, or other inappropriate objects.
• Before you jump or step on the platform, be certain that it will not skid or move
and that you will land with your foot or feet entirely on the platform, not hanging
over the edge.
• Use the platform away from objects that may interfere with your movements or
injure you if you fall.
• Follow all other safety rules and guidelines that apply to you.
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Force Platform Suggested Activities
Suggested Activities
Hang Time
Stand on the platform and jump vertically. Look at a graph of force versus time to
determine your “hang time,” or how much time you spend in the air. Is you hang time
related to how high you jump? What other factor affect hang time?
For more precise time measurements, use a higher sampling rate.
Vertical Impulse
Use a motion sensor (CI-6742) to measure the position and velocity of the top your
head as you jump on the platform. What is your measured vertical velocity at the
moment your feet leave the platform? If you assume that you are a point mass, does
this velocity correspond with your measured hang time? Why not?
Stand on the platform and press the tare button. Bend your knees and jump with a one
smooth motion. The area under the force versus time plot is the impulse. How does
the impulse of jumping compare to the impulse of landing? Using the measured
impulse, calculate your launch velocity.
Compare the velocity measured by a motion sensor to the velocity calculated from the
impulse. Why are they not necessarily equal?
Horizontal Impulse
Hang the Force Platform on a wall. Press the tare button. Sit on a rolling chair, a
kinesthetics cart (SE-8747), or a hovercraft (ME-9838) and push off against the platform. Measure the impulse, or the area under a plot of force versus time. How is the
impulse related to your momentum immediately after pushing off?
Use a motion sensor (CI-6742) to measure your velocity as you push off. Use this
velocity to calculate your momentum and compare it to the impulse. (Remember to
take into account the mass of the person and the chair, cart, or hovercraft.)
Motion Sensor
Force Distribution (With Two Platforms)
Place two Force Platforms on
the floor, and place two parallel
boards (as pictured) to act as a
bridge. Press the tare buttons.
Place a heavy ball on the
boards. Set up a motion sensor
(CI-6742) to measure the position of the ball. While collecting
data, give the ball a push so that
it rolls along the boards.
What is the relationship between the position of the ball and the
force measured by each platform? How does the sum of the forces change?
Calculate the changing torques applied to the boards by each platform and the ball as
the ball rolls. How does the sum of the torques change?
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Model No. CI-6461 Specifications
Specifications
Range −1100 N to +4400 N (−250 pounds to +1000 pounds)
Accuracy ±4.4 N (±1 pound) or 1% of reading, whichever is greater
Resolution 0.34 N with
2.75 N max.
Zero (Tare) Function Push Button
Platform Size 35 cm × 35 cm
Mass 4 kg
Force Overload Protection Up to 6600 N (1500 pounds; 1700 N or 375 pounds per beam)
ScienceWorkshop
750 Interface at 100 Hz or less
Technical Support
For assistance with any PASCO product, contact PASCO at:
Address: PASCO scientific
10101 Foothills Blvd.
Roseville, CA 95747-7100
Phone: 916-786-3800 (worldwide)
800-772-8700 (U.S.)
Fax: (916) 786-3292
Web: www.pasco.com
Email: support@pasco.com
Limited Warranty
For a description of the product warranty, see the PASCO catalog.
Copyright
The PASCO scientific 012-09493A
non-profit educational institutions for reproduction of any part of this manual, providing the reproductions are used only in their laboratories and classrooms, and are not sold for profit. Reproduction under any other circumstances, without the written consent of PASCO
scientific, is prohibited.
Trademarks
PASCO, PASCO scientific, DataStudio, and ScienceWorkshop are trademarks or registered trademarks of PASCO scientific, in the
United States and/or in other countries. All other brands, products, or service names are or may be trademarks or service marks of,
and are used to identify, products or services of, their respective owners. For more information visit www.pasco.com/legal.
Force Platform Instruction Manual
is copyrighted with all rights reserved. Permission is granted to
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