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Model No. PS-2138

Goniometer

9

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Experiment

In this activity you will rotate your arm about your elbow and investigate 
how the position, velocity and acceleration of your hand relate to the 
angle, angular velocity and angular acceleration of your arm.

Part 1: Arc Length vs. Angle

When you rotate your forearm about your elbow (while keeping your upper 
arm stationary) your hand traces out an arc, or part of a circle. You will use 
a pen and white board to mark the path of your hand. The Goniometer will 
measure the angle through which your forearm rotates.

Setup

1.

Connect the Goniometer to the interface.

2.

Mount the Goniometer on your elbow

*

 so that a flexion of the joint is 

measured as a positive angular displacement (as pictured below).

3.

Stand next to the white board with your arm relaxed at your side. Let 
your elbow and the 

back

 of your hand touch the board.

Equipment

Part Number

Goniometer Probe

PS-2138

Angle Sensor

PS-2139

PASPORT interface or interfaces

(one multi-port interface or two single port interfaces)

See PASCO catalog or www.pasco.com

Motion Sensor

PS-2103

Acceleration Sensor

PS-2118, PS-2119 or PS-2136

Wall-mounted white board and pen

*If you are right-
handed, mount the 
Goniometer on your 
right elbow; if you 
are left-handed, 
mount it on your left 
elbow.

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Summary of Contents for Pasport PS-2138

Page 1: ...Instruction Manual No 012 08904A Goniometer PS 2138 PS 2137...

Page 2: ...ts Introduction 3 Probe Mounting 4 Sensor Setup 5 Suggested Activities 6 Experiment 9 Experiment Teachers Notes and Sample Data 19 Other Sample Data 23 Safety 25 Specifications 25 Technical Support 25...

Page 3: ...ms and legs as experimental apparatus The Goniometer in conjunction with a PASPORT interface measures and records the angle angular velocity and angular acceleration of an elbow knee or hip The sensor...

Page 4: ...ng straps can be used in two ways The easier method is to place the straps on the limbs then stick the probe to the outside of the straps For more secure attachment tuck the probe arms inside the over...

Page 5: ...al Align the probe s hinge with the hip joint Attach one arm of the probe to the thigh parallel to the tibia Have the subject stand on both feet attach the other probe arm vertically to the waist stra...

Page 6: ...tion Explain what you observe Collect angle data of the hips during walking fast walking and running How does the angle of forward rotation compare to the angle of backward rotation Compare the left a...

Page 7: ...bject standing on the opposite foot on a low surface Leg with knee bent at right angle freely dangling about the hip Do angle angular velocity and angular acceleration approximate simple harmonic moti...

Page 8: ...Goniometer Suggested Activities 8...

Page 9: ...orearm rotates Setup 1 Connect the Goniometer to the interface 2 Mount the Goniometer on your elbow so that a flexion of the joint is measured as a positive angular displacement as pictured below 3 St...

Page 10: ...the pen Distance from elbow to pen Procedure 1 Fully extend your elbow and place the pen tip on the board 2 Start data collection 3 Draw an arc on the board by flexing your elbow Move only your forear...

Page 11: ...o the pen s r According to this theoretical relationship and your measured values of and r how far did your hand travel s theoretical 3 Measure the length of the arc that you drew and record it below...

Page 12: ...ar velocity of your forearm equals the change in angle divided by the change in time t t In Part 1 you discovered that the relationship between arc length and angle is s r thus s r Predict You will us...

Page 13: ...rom the sensor 3 Stop data collection Analysis In this analysis use units of m s for velocity and rad s for angular velocity 1 Look at graphs of Velocity vs Time and Angular Velocity vs Time together...

Page 14: ...est fit line in terms of vT and slope Does the relationship represented by this equation support the prediction that you made earlier 5 What physical quantity is represented by the slope Measure this...

Page 15: ...t The angular acceleration of your forearm equals the change in angular velocity divided by the change in time t t In Part 2 you discovered that the relationship between tangential velocity and angula...

Page 16: ...he picture 5 Measure the distance r from your elbow to the Acceleration Sensor r 6 Hold your arm so that your forearm will rotate in a horizontal plane as pictured and the X Y plane of the Acceleratio...

Page 17: ...ion vs Angular Acceleration and apply a linear fit What is the slope of the best fit line including units 3 Write the equation of the best fit line in terms of aT and slope Does the relationship repre...

Page 18: ...hand toward or away from your elbow 8 Create a graph of Centripetal Acceleration vs Angular Velocity The theoretical relationship between Centripetal Acceleration aC and Angular Velocity is aC r 2 whe...

Page 19: ...1 In this example r 0 38 m 1 Arc Angle 1 42 rad 2 s r 0 38 m 1 42 rad 0 54 m theoretical 3 s 0 57 m actual 4 In this example the theoretical and actual values of s differ by 5 Part 2 Students should p...

Page 20: ...to the hand In this case the actual value of r is 0 36 m The theoretical value from slope and actual value from direct measurement differ by about 8 Note that the directly measured values of r in Par...

Page 21: ...pe is equal to r In this case the actual value is 0 36 m The theoretical value from slope and actual value from direct measurement differ by about 24 5 The graphs of Angular Velocity vs Time and Centr...

Page 22: ...aC versus 2 the slope of the best fit line is the theoretical value of r in this case 0 232 m 0 008 m 10 The theoretical and actual values of r differ by about 55 In Part 3 your students will probably...

Page 23: ...ntribute to precision and accuracy of the collected data Other Sample Data Simple Harmonic Motion of the leg rotating about the hip dangling freely and oscillating at its natural frequency with the kn...

Page 24: ...and amplitude The angle top and angular velocity bottom of the hip while walking The maximum slope of the angle plot is about 1 9 rad s equal to the maximum value of angular velocity Angle data from t...

Page 25: ...e 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 800 772 8700 Fax 916 786 3292 Web ww...

Page 26: ......

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