Projects: UDL : UDL Friction Activity 5-6 Get moving
This page last changed on Oct 29, 2007 by ehazzard.
How strong is the force of friction?
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He decided his experiment would look like this:
Here is a graph of force against time. Suppose you pushed very lightly on the force sensor, then harder and harder until the box started sliding. Predict what your graph would look like.
Find a small cardboard box. Find a water bottle that fits into the box and fill it with water.
Attach the force sensor to the computer. Push the box with the force sensor.
Start recording with the force sensor. Gradually push harder and harder until the box starts to slide. Keep pulling so that the box slides at a constant speed.
Stop recording. Label your graph. Mark where you first started pushing. Mark where the box first started to move. Mark the greatest force value.
What was the greatest force value?
Describe your graph. What did it look like before the box started moving? What happened just when the box started moving? What happened after that?
What would you say was the average value of the friction force needed to keep the box moving?
Do you think you would get the same results if you were pulling on the box instead of pushing?
Why do you think so?
Now explore ways to increase or decrease the friction force. You can save several experiments on the same graph. Each button of the left is a different dataset. The first one, called "trial 1", is your data pushing the box. Use "trial 2", "trial 3", and "trial 4" for other materials.
Try putting waxed paper under the box. Attach it with tape on the sides. Select "trial 2" and repeat your experiment. Be sure to label the new line you have made on your graph.
Record the average value of the moving friction force. Does waxed paper increase or decrease the friction force?
Try another material, such as aluminum foil, under the box. Attach it with tape on the sides. Select "trial 3" and repeat your experiment. Be sure to label the new line you have made on your graph.
Record the average value of the moving friction force for Trial 3.
If you have sandpaper, put it under the box and attach it with tape to the sides. If you don't have sandpaper, find some other material that you think has a high friction value. Select "trial 4" and repeat your experiment. Be sure to label the new line you have made on your graph.
Record the average value of the moving friction force for Trial 4.
Fill out the following table.
Which surface had the most friction? Which had the least friction?
Is this what you expected?
If you could zoom in on the surface between the material and the table top for each material, how do you think the most slippery one would be different from the most sticky one?
How would this difference help explain the difference in friction value?
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