Equipment

Ring Stand, Force Sensor, Dynamics Track, Motion Detector, Dynamics Cart, LabPro, Computer w/ Logger Pro software

Diagram

Basic Procedure

Force vs. Time Collection

1. Note: You will collect data for impulse first, then go on to collect data for change in momentum.
    
2. Plug Force Sensor into LabPro. Mount Force Sensor on ring stand that has been clamped to table. Adjust the height so the plunger on the dynamics cart pushes directly against the hook on the Force Sensor.
    
3. Set up the data collection:
   • Click on the Data Collection button (stopwatch icon).
   • Set the time to 0.5 sec at a rate of 1000 samples per second.
   • Click on Trigger and turn on triggering.
   • Set the trigger level to be -2 newtons and collect 20 points before trigger. (The Force Sensor considers pushing forces to be negative, pulling forces positive.)
   • After clicking [DONE], click on the Zero button to zero the Force Sensor reading.
      
4. Depress the plunger on the cart one click and move it next to the Force Sensor so the two are touching. Keep the contact force to a minimum.
    
5. Start data collection by pressing [F11] or the Collect button. The screen should say "Waiting for Trigger or Data".
    
6. Depress the release on the cart to allow the plunger to extend, pushing against the Force Sensor.
    
7. Analyzing the data:
   • Drag across the portion of the graph which shows the force vs. time while the plunger was extending. Click on the Integrate button on the menu bar to get the area under this graph. If the area is negative, use the absolute value. Record this area and the units in the data table.
      
8. Repeat the steps above using the second and third clicks on the plunger.

Motion Collection

1. Unplug the Force Sensor and plug a Motion Detector into Dig/Sonic1. Place the Motion Detector at the far end of the dynamics track facing the cart.
    
2. Set up data collection:
   • Click on the Data Collection button (stopwatch icon).
   • Set the time to 5 sec at a rate of 30 samples per second.
   • Click on Trigger and make sure triggering is turned off.
      
3. Depress the plunger on the cart one click and move it next to the Force Sensor so the two are touching.
    
4. Start data collection by pressing [F11] or the Collect button. As you see the graph line beginning to move across the screen, depress the release on the cart to allow the plunger to extend, pushing against the Force Sensor.
    
5. Analyzing the data:
   • Click and drag across the position vs. time graph corresponding to the cart moving after the "explosion". Click on the Linear Fit button to determine the slope of the graph.
   • Click and drag across the velocity vs. time graph corresponding to the cart moving. Click on the Statistics button to determine the maximum velocity of the cart. Compare your two values to see how consistent they are.
   • Record the maximum velocity value in your data table.
      
6. Repeat the steps above using the second and third clicks on the plunger.

Analysis:

1. Multiply the mass of the cart by the maximum velocity to get the momentum the cart had when it left the "explosion" in each case.
    
2. Compare the gain in momentum of the cart in each case with the area under the Force vs. Time graph which is the Impulse given to the cart. What is the percentage difference in each case? Enter that value in the data table.
    
3. Was the resulting momentum of the cart equal to, less than, or more than the impulse in each case? Does this pattern make sense? What led to this pattern?

Data Table:

Mass of Cart: _________________ kg

 

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MS Word computer version - ImpulseLab.doc

pdf computer version - ImpulseLab.pdf

   

C. Bakken
November 2004