In this experiment, students determine the coefficient of kinetic friction for an object on an incline.

• Microsoft Word version of this lab:
  
  PASPORT: (Zip file | Stuffit file)
  ScienceWorkshop: (Zip file | Stuffit file)

• Motion Sensor:  PASPORT (PS-2103) | ScienceWorkshop (CI-6742)
• Dynamics System: 1.2 m Classic Dynamics System (ME-9429A) | 1.2 m PAScar Dynamics System (ME-6955)
• Large Base and Rod (ME-9355)
• Mass and Hanger Set (1/2 g resolution) (ME-8979)
• Angle Indicator (ME-9495)
• Computer Interface:
     PASPORT: Xplorer GLX | Xplorer | USB Link | PowerLink
     ScienceWorkshop: 500 | 750 (SCSI) | 750 (USB)

PART 1:

1. Record the mass of the block.


2. Place the block with the wooden, broad side down on the adjustable end of the track.


3. Adjust the angle of the incline until the block slides down the incline with a brief push.


4. Return the block to the upper end of the track. Again, give it a brief push down the track.


5. Press the START button in DataStudio.


6. Press the STOP button in DataStudio when the block comes to a stop.


7. Repeat steps 2-5 until the block slides down the incline at a constant velocity. Note: It may be helpful to delete unwanted data. Go to the Experiment Menu in DataStudio and select "Delete Last Data Run."


8. Record the angle in Data Table 1 below.


9. Repeat steps 2-8 for the other 3 sides of the block (See Data Table 1).

Data Table 1:

Mass of block: ___________________

Trial	Angle (degrees)
1. Wooden side, broad
2. Wooden side, narrow
3. Felt side, broad
4. Felt side, narrow

-- PASPORT users -- See Set Up for Part 2

-- ScienceWorkshop users -- See Set Up for Part 2

PART 2:

1. Adjust the angle of the track to 5 degrees.


2. Place just enough mass on the hanger so that the block slides up the track.


3. Return the block to the lower end of the track. Again, give it a brief push up the track.


4. Press the START button in DataStudio.


5. Press the STOP button in DataStudio when the block comes to a stop or before it strikes the Super Pulley.


6. Repeat steps 2-5 until the block slides up the incline at a constant velocity. Note: It may be helpful to delete unwanted data. Go to the Experiment Menu in DataStudio and select "Delete Last Data Run."


7. Record the hanging mass in Data Table 2 below.


8. Repeat steps 2-7 for the other 15, 25 and 35 degrees.

Data Table 2:

Angle (degrees)	Mass (kg)
5
15
25
35

PART 1:

1. For Part 1 of the experiment, draw a quantitative force diagram for the block as it slides down the track on its:
   • Broad, felt side
   • Narrow, felt side
   • Broad, wooden side
   • Narrow, wooden side


2. Calculate the coefficient of kinetic friction for the:
   • Broad, felt side
   • Narrow, felt side
   • Broad, wooden side
   • Narrow, wooden side


3. Using your fingers, feel the felt on both the narrow and broad sides. Can you detect a difference in the friction? Do the results from the experiment show a difference in the friction? Explain.


4. Using your fingers, feel the wood on both the narrow and broad sides. Can you detect a difference in the friction? Do the results from the experiment show a difference in the friction? Explain.


5. Does the coefficient of kinetic friction depend on the area that is in contact? Explain.

PART 2:

1. For part 2 of the experiment, draw a quantitative force diagram for the block as it slides up the track at:
   • 5 degrees
   • 15 degrees
   • 25 degrees
   • 35 degrees


2. Calculate the coefficient of kinetic friction for the block as it slides up the track at:
   • 5 degrees
   • 15 degrees
   • 25 degrees
   • 35 degrees


3. Does the coefficient of kinetic friction depend on the angle of the incline? Explain.


4. Explain why, in determining the coefficient of kinetic friction, the block is given a push.