Name ____________________________________ Date __________________
Friction
ESSENTIAL QUESTIONS
How does friction affect the force necessary to accelerate an object?
How do different surfaces compare in the amount of friction acting on an object?
OBJECTIVES
In this experiment, you will
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Use a computer to measure sliding friction.
Measure friction between a different surfaces sliding on one another. .
Make predictions about other surfaces.
Test your predictions.
MATERIALS
computer
Vernier computer interface
Vernier Force Sensor
wooden block (with a hook)
paper clip
sandpaper
Lab table
Dual-Range
Force Sensor
Figure 1
PROCEDURE
Part I Varying Sized Objects
1. Connect the force sensor to the LabQuest 2 interface. If you are using a Dual-Range Force
Sensor, set the range switch to 10 N.
2. Open Logger Pro from the desktop of the computer. (You should see a box with Position data
in meters under the data table, as well as a position vs time and a velocity vs time graph.)
2. Zero the Force Sensor.
a. Lay the Force Sensor on the tabletop in the position shown in Figure 1.
b. Click
(next to the collect button) to zero the sensor.
3. Get a wooden block (with a hook on one end). Attach the Force Sensor to the hook on to the
sand paper block.
Middle School Science with Vernier
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Friction
4. Place the wooden block on the scale, measure and record its mass. Calculate its Force of
Weight in Newtons using the formula W=mg. Do this with 2 blocks stacked on top of each
other as well.
5. You will measure friction as the block is pulled across the 3 surfaces. In the space provided
in the data table Part II below, predict the order of friction for these surfaces—from lowest to
highest.
6. Go to the “Experiment” menu at the top and select “Data Collection”. Change the sampling
rate to 10 samples/second.
7. Slowly pull the wooden block across a piece of particle board with a smooth surface. Hold
the Force Sensor by its handle and pull it to you at a constant rate, as demonstrated by your
teacher. The Force Sensor should be held parallel to and about 1 cm above the surface. Once
the wooden block is moving at a steady rate, click
to begin data collection. Click end
before reaching the end of the board.
8. After the data have been collected, look at the graph displayed on the screen. If the graph is
reasonably flat, proceed to Step 6. If there are big peaks and valleys, repeat Step 6.
9. Click the Statistics button,
. Record the Mean (average) force (in N).
10. Repeat Steps 6-8 as you pull the block across all 3 surfaces. Record data.
11. Repeat Steps 6-8 as you pull 2 blocks across the 3 surfaces. Record data.
DATA
Part I Block Measurements
Block Size
1 block
2 blocks
Mass (g)
Force (N)
Part II Predicting friction
Predicted order of values for particle board, wood, and cloth
(Lowest)
(Highest)
Part III Experimental Trials
Surface
Particle Board
Wood
Cloth
Force (N)- 1 block
Force (N)- 2 blocks
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Middle School Science with Vernier
Name ______________________________________________ Date ___________________________
ANALYZING THE DATA
1. How did having two blocks affect the force needed to move your object compared to one?
2. What is the effect of surface roughness on friction?
3. How did you decide the order of your predictions in Part II?
4. How good were your predictions? Explain.
5. Give two examples of situations where friction is helpful.
6. Give two examples of situations where it is best to reduce friction.
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Friction
CONCLUSIONS
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Middle School Science with Vernier