FRICTION LAB (FORMAL LAB) Purpose: The objectives of this experiment are to analyze a force of friction vs. time graph to determine the coefficients of static and kinetic friction between a friction cart of your choice and the aluminum ramp. Construct a graph to study the relationship between the force of friction and the normal force. Procedure: 1. Obtain the necessary materials-iPad, Airlink, USB cable, power cord, force meter, felt or Plastic bottom friction tray, ramp, constant velocity car, and a mass set. 2. Boot the computer and connect the Airlink and force meter via Blur Tooth to the iPad of one of the members of the lab group. Check the number on your AirLink to make sure that you are connected to the correct one for your group. 3. Click on the Sparkvue App. The App should detect the force meter. If needed click on “ Force Pull Positive”. 4. Maximize the force vs. time graph. 5. Connect the force meter to the top of the constant velocity car using the attaching screw. 6. Place 1000g into the tray and place the loop of string around the hook on the force meter. 7. Before you start and before every data run, ZERO THE FORCE METER by pressing on the zero button on the force meter, while making sure that there is no force on the force meter (keep the string slack) as you do so. 8. Click ‘start (green play button)’ to begin taking data, THEN turn on the constant velocity car (keeping it at a low setting) to pull the friction tray over the ramp. 9. After 2 or 3 seconds, click the stop button to stop taking data and turn the constant velocity car off. 10. Click on the scaling button if necessary. 11. Use the pointer arrow to determine the maximum static force of friction and the average kinetic force of friction for your run. Record these in a data table. 12. Add more mass to the tray (100g increments work well) and repeat steps 7-11, until you have at least 5 trials. 13. For each trial calculate the weight, normal force, and the coefficients of static and kinetic friction. 14. Construct graphs of Frictional force vs. Normal force on EXCEL or DataAnalysis and determine the coefficients of static and kinetic friction from your graphs. 15. Write a formal lab report for your experiment, using the usual lab report format. 16. The actual values for the felt and ramp are µs= 0.327, and µk= 0.288. The actual values for the plastic and ramp are µs= 0.206, and µk= 0.153. Use these values to compute the % error. Note about formal lab report: Theory section: Include an additional Theory section where you state all the formulas you used Include a free body diagram in this section and Include a sketch of the Friction vs. Time graph that you observed on Data Studio. Label the various sections of the graph. Formula for percent error: Percent Error = (| measured value – actual value|)/actual value * 100%
